“Children whose mothers are depressed during pregnancy have a small increased risk of depression in adulthood,” BBC News reports.

In this study researchers looked at whether antenatal depression (depression during pregnancy) and postnatal depression in mothers was associated with a higher risk of depression in their children in late adolescence.

They found that, at the age of 18, adolescents had a small increased risk of having depression if their mother had antenatal depression. However, the link between postnatal depression and later depression in the offspring was only present in cases where the mother had a lower level of education. The researchers took level of education to be a marker of socioeconomic status.

The strengths of this study include its size (there were more than 8,000 participants) and its length (around twenty years).

The main limitation is that it is still difficult to say for certain that maternal depression during pregnancy or after birth directly influences risk of depression in offspring later.

The researchers speculate that antenatal depression could increase levels of stress hormones which could affect the development of the baby. This cannot be proven by the evidence presented in this study. Depression is a complex condition, and likely to be influenced by both genetic and environmental factors.

Pregnant women should not worry unduly about whether their moods can affect their unborn child. The important thing is to seek help if you think you are experiencing symptoms of depression.

Depression during pregnancy

There is a lot of publicity about postnatal depression, but little is said about antenatal depression. But antenatal depression is more common than most people realise. A recent study estimated that around one in five women are affected.

Being pregnant can be extremely stressful. One expert said she wasn’t surprised that some pregnant women were affected by depression, she was surprised that all women were not affected.

Read more about feelings and relationships during pregnancy in the NHS Choices Pregnancy and Baby Guide.

Where did the story come from?

The study was carried out by researchers from the University of Bristol, University of London, Oxford University and the University of Rochester in the US. It was funded by the Wellcome Trust, the National Institutes of Health in the US and the United Kingdom Medical Research Council.

The study was published in the peer-reviewed Journal of the American Association (JAMA) Archives of Psychiatry.

In general, it was covered accurately if uncritically in the press. The Daily Mail’s phrasing made the risk of depression in offspring of mothers who had been depressed in pregnancy seem larger than it is. And BBC News made an error when it reported that the study involved “more than 8,000 mothers with depression”. The study involved 8,937 mothers for whom data on antenatal and postnatal depression was available. This does not mean they were all depressed.

What kind of research was this?

This was a prospective cohort study that looked at whether there was a link between maternal antenatal and postnatal depression and depression in their offspring.

The authors point out that depression in late adolescence is a major public health issue. They say that there have been few studies looking at whether antenatal or postnatal depression in the mother is a risk factor.

A prospective cohort study is the best way to look at the link between exposures (in this case maternal antenatal or postnatal depression) and later outcomes (in this case offspring depression). The main limitation of the study design is that many factors can affect the risk of depression, and it is difficult to rule out the possibility that factors other than the one being studied are influencing any link seen.

Researchers can take steps to reduce the impact of these factors (known as confounders) on their analyses, but there is always the possibility that there are further confounders.

What did the research involve?

The researchers used data from a large study of pregnant women due to deliver in 1991 and 1992, called the Avon Longitudinal Study of Parents and Children (ALSPAC). They assessed antenatal and postnatal depression in the participating mothers, and then assessed whether any of their children had depression when they reached the age of 18.

The ALSPAC study recruited the children from 15,247 pregnancies. The current study looked at 8,937 of the women for whom data on antenatal depression (abbreviated to AND) and postnatal depression (PND) was available.

Symptoms of antenatal and postnatal depression in the mothers and in the fathers were measured using the Edinburgh Postnatal Depression Scale (EPDS). This is a standard 10-item self-report depression questionnaire used for postnatal depression.

The questionnaires were sent by post at approximately 18 and 32 weeks of the pregnancy and when the child was aged eight weeks and eight months.

The same depression scale was used to measure maternal depression repeatedly up until the child reached the age of 12 years.

Fathers also completed the depression questionnaire at 18 weeks of pregnancy and eight months postnatally.

Mothers also completed questionnaires about other factors that could affect results (potential confounders). This included:

• Their education and their partner’s education
• Maternal age
• Social class
• Number of other children
• History of depression before pregnancy
• Smoking during pregnancy
• Breastfeeding in the first year
• Use of non-parental childcare within the first six months of the child’s life

When the children reached the age of 18, they were assessed for major depression using a self-administered, computerised version of a validated clinical interview. Only 4,566 of the offspring were assessed for depression at the age of 18.

Researchers then carried out various analyses of the association between both maternal AND and PND symptoms and depression in the offspring at the age of 18. They took into account the potential confounders in their analyses. They also analysed whether the mother’s education had an impact on any associations between AND and PND, and depression in the 18-year-old offspring. They carried out similar analyses for the fathers, but they focused on the mothers.

What were the basic results?

The researchers report that 11.6% of the 8,937 women reported symptoms which classified them as having AND, and 7.4% had symptoms which classified them as having PND. When analysing the relationship between maternal and paternal perinatal depression and risk of offspring depression they found that:

• After taking into account potential confounders, including later depression, antenatal depression in the mother was associated with depression in their offspring at 18 years. For every five-point increase in maternal depression score antenatally, the odds of the offspring having depression at the age of 18 years was 1.28 times higher (95% Confidence interval (CI), 1.08 to 1.51). This relationship did not appear to be affected by maternal education.
• There was also an association between mothers with postnatal depression and depression in their offspring at 18 years, but this was weakened when potential confounders were taken into account, and the link varied depending on maternal education. Maternal PND in mothers with lower levels of education was associated with offspring depression (odds ratio [OR] 1.26, 95% CI 1.06 to 1.50 for a five-point increase in postnatal depression score). The link was not statistically significant among mothers with higher levels of education.
• Fathers’ depression antenatally was not associated with offspring depression. Postnatally, paternal depression was associated with offspring depression but, again, this was limited to fathers who had lower levels of education.

The authors say that their findings suggest that treating maternal depression during pregnancy could prevent depression in their offspring during adulthood. They also say that prioritising less advantaged mothers postnatally may be most effective in preventing depression in adolescent children.

They say that their findings suggest that while antenatal depression may be transmitted from mother to foetus by a biological mechanism, the risk of PND associated with offspring depression is environmental and can be modified by factors like psychosocial support. They also raise the possibility that transmission of depression from mother to child may be genetic.

Conclusion

The strengths of this study lie in its large sample, long-term follow-up and also the repeated measures of maternal depression conducted by researchers.

However, it also had some limitations:

• Data was only available for about half the adolescents of mothers involved in the study, and those that took part tended to have higher socioeconomic status than the average for the whole original sample. This could introduce selection bias.
• The method used to assess maternal depression was a valid way to measure depression symptoms, but a formal depression diagnosis requires a more thorough clinical interview.
• Maternal depression was only measured up until the child reached 12 years of age, so it is uncertain if maternal depression after this point might have been associated with their offspring’s depression.
• Although the study adjusted results for factors that might affect the risk of depression, such as parental income, it did not take into account other factors that could affect risk of depression in adolescents, such as external pressures relating to school and peer group.
• The study did not assess whether the women were receiving treatment for their depression and how this might have influenced results.

Depression is a complex condition, and there are likely to be many factors influencing our risk of developing it. While this study suggests that there may be a link between maternal antenatal and postnatal depression and offspring depression, it cannot say for certain why this is the case, and whether these factors are directly influencing risk.

Further research is likely to continue in this area.

Depression during pregnancy and postnatally should always be taken seriously, and women who are experiencing depressive symptoms should seek help.

You may be depressed if, during the past month:

• You have often been bothered by feeling down, depressed or hopeless
• You take little or no pleasure in doing things that normally make you happy

If you experience either or both of these symptoms you should contact your GP for advice.

For more information about depression and low mood visit the NHS Choices Moodzone.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Summary

“Children whose mothers are depressed during pregnancy have a small increased risk of depression in adulthood,” BBC News reports. In this study, researchers looked at whether antenatal depression (depression during pregnancy).

Links to Headlines

• Depression risk ‘starts in the womb’. BBC News, October 10 2013
• Depression in pregnancy may affect children’s mental health, study finds. The Guardian, October 9 2013
• How a mother’s depression in pregnancy hits children when they reach teens: Stress hormone in the womb could make the risk one-and-a-half times higher. Mail Online, October 10 2013

Links to Science

• Pearson RM, Evans J, Kounali D, et al. Maternal Depression During Pregnancy and the Postnatal Period – Risks and Possible Mechanisms for Offspring Depression at Age 18 years. JAMA Psychiatry. Published online October 9 2013

From www.nhs.uk

“Children with regular bedtimes less likely to misbehave, research shows,” The Guardian reports. The advice is prompted by a new study into the effects of irregular bedtimes on children’s behaviour.

The researchers studied more than 10,000 children whose behaviour and bedtime patterns were monitored when they were aged three, five and seven years.

It found children who had non-regular bedtimes had more behavioural problems over the years than those who had regular bedtimes. This was assessed using a validated mother- and teacher-completed behaviour questionnaire.

Encouragingly, the association between irregular bedtime and misbehaviour appears to be reversible. Many children with a previous history of ‘acting up’ experienced an improvement in behaviour once their bedtime patterns were better regulated.

One suggested explanation for the results was that those with non-regular bedtimes were getting less sleep. This could, potentially, affect the development of regions of the brain associated with behaviour regulation. However, they didn’t measure sleep directly so this remains an assumption.

This study alone cannot prove that other factors aside from bedtime patterns weren’t also influencing behaviour. Child behaviour is an incredibly complex area and many factors have the potential to affect it.

With these limitations in mind, setting a regular bedtime schedule is thought by most childcare experts to be an effective method of making sure your child gets the right amount, and improves the quality, of sleep.

Read more Healthy sleep tips for children.

Where did the story come from?

The study was carried out by researchers from University College London and was funded by a grant from the UK Economic and Social Research Council.

The study was published in the peer-reviewed medical journal Pediatrics.

Overall the media reporting of the study appeared accurate. Though the inherent limitation of the study – the fact that other, unaccounted for, factors may have been influencing behaviour (confounders) was not discussed.

What kind of research was this?

This was a cohort study measuring bedtime information and behavioural difficulties of the same group of children over a period of four years.

The study reported that the causal links between disrupted sleep and behavioural problems are not clear. So their study aimed to address the issue by answering the following questions:

• Are bedtime schedules associated with behavioural difficulties?
• Do effects of bedtime schedules on behaviour build up over early childhood?
• Are changes in bedtime schedules linked to changes in behaviour?

A cohort study is useful for measuring changes over time, such as the impact of changes in bedtime patterns and behaviour. Limitations of this approach are discussed in the conclusions section.

A randomised control trial would be a more effective way to assess the impact of bedtime patterns on behaviour but this would be problematic to perform for practical and ethical reasons.

What did the research involve?

Information from 10,230 seven-year-olds from the UK Millennium Cohort Study was analysed – this is an on-going cohort study involving children born around the turn of the millennium. Bedtime information was collected at three, five and seven years, alongside behavioural difficulties scores as rated by mothers and teachers.

At three, five and seven year time points the child’s mother was asked, “On weekdays during term-time, does your child go to bed at a regular time?” (response categories were always, usually, sometimes, and never). These were then categorised into either “regular bedtime” (always or usually) or “non-regular bedtime” (sometimes or never) for analysis. Questions were not asked about bedtimes on weekends.

Behavioural difficulties were assessed by teachers and mothers who were asked to complete a validated questionnaire called the Strengths and Difficulties Questionnaire (SDQ), age four to 15 years version.

The SDQ asks questions about five domains of social and emotional behaviour, namely conduct problems (or in layman’s terms “being naughty”), hyperactivity, emotional symptoms, peer problems, and prosocial behaviour (behaviour intended to benefit others).

Scores from the first four domains are combined to construct a total difficulties score.

Children with attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorder were excluded from the study.

The analysis took into account observed reductions in behavioural difficulties scores as children get older, alongside numerous other potentially influential factors, known as confounders, such as household income, highest parental education, birth order of the child and psychological distress experienced by the mother.

What were the basic results?

In describing the study cohort the authors noted that children without regular bedtimes and those with later bedtimes (9 PM or later) had more socially disadvantaged profiles. For example, they were more likely to be from the poorest homes, have parents without degree level qualifications, and have mothers with poorer mental health. This was later adjusted for in the statistical analysis.

The main findings were:

• There was an incremental worsening (“dose-dependent”) in behavioural scores the longer children were exposed to non-regular bedtimes. Behavioural scores got worse compared to those with regular bedtimes as they progressed through age three, to age five to age seven. The behavioural deterioration was reported by both mothers and teachers.
• Children who changed from non-regular to regular bedtimes had statistically significant improvements in behavioural scores, changes that were described as “nontrivial” by the study authors.
• For children who changed from regular to non-regular bedtimes between ages five and seven there was a statistically significant worsening in scores.

The researchers’ main conclusions were that “having regular bedtimes during early childhood is an important influence on children’s behaviour” and that in light of the apparent reversibility of the bad effects “there are clear opportunities for interventions aimed at supporting family routines that could have important impacts on health throughout life”.

Conclusion

This large cohort study indicates that seven-year-old children with non-regular bedtimes have more behavioural difficulties, as reported by both mothers and teachers using a questionnaire, than children who had regular bedtimes.

There appeared to be a dose dependent relationship with the behaviour gap between regular and non-regular bedtimes widening as the children got older (from three to seven years old).

The behaviour-bedtime relationship appeared to be reversible in both directions as children who adopted new regular bedtimes improved behaviour and those who went from regular bedtimes to non-regular showed signs of deterioration.

There are a number of factors that need to be taken into account when considering the evidence provided by the researchers.

Confounders

The study went to great lengths to adjust for common confounders that could account for differences in behavioural difficulties in children, other than potential lack of sleep due to irregular bedtimes.

Despite their efforts, as behaviour is influenced by so many factors, we cannot be sure that the differences observed are only due to bedtime patterns.

For instance, there may still be important factors, not measured in the study that have influenced these results, such as other unmeasured environmental and lifestyle habits. These could include the child’s diet and exercise, the type of games and other activities they take part in, use of electrical devices such as smartphones or tablets, number of people in the house, mental health history of the father, ethnic background and so on.

What constitutes a meaningful effect?

Another main consideration for this type of study is the magnitude of difference reported in behavioural difficulties between the regular and non-regular bedtime groups, and whether this is meaningful to the person or parents involved.

The study authors stated that a 0.9-point difference in behavioural scores would correspond to a small meaningful difference and that a 2.3-point difference would correspond to a moderate meaningful difference. Additionally, they reported a 1-point difference in behavioural difficulties scores has been shown elsewhere to predict clinically diagnosed problems. It is not clear if these definitions are accurate or whether the parents would agree that these changes were meaningful.

The magnitude of the behavioural differences shown in the study between the two bedtime groups ranged from 0.5 points to 2 points, so using the authors’ guide they appear to be small to moderately meaningful differences.

A change from non-regular to regular bedtimes between ages five and seven corresponded to a behavioural improvement of 1.02 points, suggesting many of the negative effects of non-regular bedtimes may be reversed.

The magnitude of a change from three years to seven years, was slightly less at 0.63 points.

Excluded groups

It should also be noted that none of the children in this study had diagnosed problems such as ADHD, so it is unclear what effect bedtime patterns would have on children with these sorts of chronic conditions.

Loss to follow-up

The study lost touch with approximately 12% of participants in the original cohort. They took reasonable steps to address this missing information in the analysis so this is unlikely to be a source of bias.

Self-reporting

A further potential limitation is that the study did not record sleep quality or quantity directly (they used regular bedtimes as a proxy measure for this) and relied on the recall of events by mothers. This may have led to recall bias based on expectations that a set bedtime is something a good mother should be doing. However, this would make it less likely to find differences between the two groups.

The bottom line is that this study suggests there may be a link between non-regular bedtimes and increased behavioural difficulties, and proposed that lack of sleep was the likely causal link.

However, this study alone cannot prove that other factors weren’t also influencing the children’s behaviour or that non-regular bedtimes or lack of sleep were the main cause of the behavioural problems.

If your child’s behaviour is causing you concern you may want to look at their sleeping habits, and if needs be, encourage a more strict weekday sleeping routine. Children need much more sleep than adults, which depending on age can range from 11 hours for a five year old to 10 hours for a nine year old. Read more about How much sleep do kids need?

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Summary

“Children with regular bedtimes less likely to misbehave, research shows,” The Guardian reports. The advice is prompted by a new study into the effects of irregular bedtimes on children’s behaviour.

Links to Headlines

• Children with regular bedtimes less likely to misbehave, research shows. The Guardian, October 14 2013
• Bedtime link to problem children: Young who do not have a regular sleep time are more likely to suffer behaviour issues. Daily Mail, October 14 2013
• Erratic bedtime shapes a child’s bad behaviour. Metro, October 14 2013

Links to Science

Kelly Y, Kelly J, Sacker A. Changes in Bedtime Schedules and Behavioral Difficulties in 7 Year Old Children. Pediatrics. Published online October 14 2013

From www.nhs.uk

“Traumatic childhoods increase the risk of death before the age of 50 by up to 80%,” reports the Mail Online.

The news is based on research that followed children born during one week in 1958 to see whether they died prematurely (before a ge 50) and to see what adverse events they went through as children.

The researchers looked at childhood adverse experiences as reported by parents and teachers when the children were 7, 11 and 16 years of age. These bad experiences included spending time in (foster*) care, suffering from neglect, parental separation, or having a family member in prison. The researchers also took into account factors such as socioeconomic status and lifestyle during childhood and when people were young adults.

Give children the best start in life

Children can’t help their circumstances. Whatever their background and experiences, one of the best things you can do for your child is to have them vaccinated against the common childhood diseases.

These often potentially fatal diseases, such as measles, can be prevented simply by a free injection available from the NHS.

Find out when to get your child vaccinated at your local GP practice.

Overall, adverse childhood experiences were associated with a higher risk of death before 50. For those who had suffered two adverse experiences, this risk was 57% higher for men and 80% higher for women, compared to those with no such experiences.

If there is a true link, we still don’t know the exact reasons. The researchers speculate that adverse events change the way the brain is wired or that people who have experienced adversity develop short-term coping strategies that lead to long-term health damage. However, this can’t be proved by the current study. It may be that as yet unaccounted for factors explain the link between adverse events and premature mortality.

Where did the story come from?

The study was carried out by researchers from INSERM (The French National Institute for health and medical research) and other French and British research organisations and universities. It was funded by the French Institut National du Cancer and the Institut de recherche en santé publique and La Ligue nationale contre le cancer.

The study was published in the peer-reviewed European Journal of Epidemiology.

The Mail Online mostly reported the results of this study accurately. However, it’s headline cherry-picked the highest premature mortality figures (those of women experiencing two or more adverse life variables). The coverage also failed to mention the limitations of the study design (although the study was large and used the most appropriate study design, cohort studies cannot show causation, only association).

What kind of research was this?

This was a cohort study. It examined whether events causing stress responses during childhood are linked to premature mortality – defined in this study as death before 50 years of age.

This is the ideal study design to investigate this issue, although it cannot prove that events causing stress responses during childhood cause premature mortality, as other factors, called confounders, could be responsible for any association seen.

What did the research involve?

The researchers used results from 7,816 men and 7,405 women who were part of a cohort study of people born during one week in 1958 in Great Britain (the 1958 National Child Development Study).

Information was collected when people were 7, 11, 16, 23, 33, 42, 46, and 50 years of age.

Childhood adverse experiences were reported by parents and teachers at 7, 11 and 16 years of age. The following were counted as adverse experiences:

• Being put into (foster*) care by age 7, 11 or 16
• Physical neglect, including being undernourished or dirty at ages 7 or 11
• Having a family member in prison or on probation (at age 11) or in contact with the probation services (age seven or all) or being imprisoned or on probation at age 16
• Being separated from their father or mother due to death, divorce or separation at 7, 11 or 16 years of age
• Having a family member with a mental illness at ages 7, 11 or 16 or having someone in the household in contact with the mental health services at ages 7 or 11
• Having a family member with an alcohol abuse problem at seven years of age

Deaths were monitored through death certificates. The researchers looked at the relationship between adverse childhood experiences and death before 50 years of age after controlling for “early life variables” and for characteristics at 23 years of age. These early life variables included:

• Mother’s age at birth
• The number of people per household
• Whether the mother’s partner was employed in manual or non-manual labour
• Mother’s educational level
• Maternal smoking during pregnancy
• Gender
• Gestational age at birth
• How many pregnancies the mother had previously had
• Birth weight
• Breastfeeding
• Congenital conditions
• Moderate/severe disabilities
• Chronic respiratory or circulatory conditions
• Sensory impairments
• Special schooling

Characteristics at 23 years of age included:

• Educational attainment
• Occupational social class
• Symptoms of depression
• Alcohol consumption
• Smoking status
• Body mass index (BMI)

What were the basic results?

• In the cohort, 70% of people had experienced no adverse childhood experiences, 22% had experienced one adverse childhood experience and 8% had experienced two or more adverse childhood experiences. Between the ages of 16 and 50 4.1% of men and 2.4% of women died.
• In men, the risk of death was 57% higher among those who had experienced two or more adversities compared to those men who had experienced none (hazard ratio (HR) 1.57, 95% confidence interval (CI) 1.13 to 2.18).
• In women, the risk of premature mortality increased with increasing number of adverse experiences. Women with one childhood adverse experience had a 66% increased risk of death (HR 1.66, 95% CI 1.19 to 2.33) and women who had had two or more had an 80% increased risk (HR 1.80, 95% CI 1.10 to 2.95) compared to women who had had none.

How did the researchers interpret the results?

The researchers conclude that the results, “point towards early life stressful events, particularly in a child’s [family] environment, being risk factors for long term health across the lifecourse and premature mortality possibly via the mechanisms of biological embedding which may occur via social, neuro-cognitive or behavioural pathways.”

Conclusion

This large cohort study found that (after taking into account early life and young adult sociological and lifestyles) being exposed to adverse childhood events was associated with an increased risk of premature death.

In men, having two or more adverse childhood experiences was associated with a 57% higher risk of death by age 50, compared to men who had none. In women, one childhood adverse experience was associated with a 66% increased risk of death, two or more was associated with an 80% increased risk of death by age 50, compared to women who’d had none.

Although the study was large, collected data as it went along (prospectively), and used the most appropriate study design, cohort studies cannot show causation, only association. And as this was a long-term cohort study, it had to deal with a significant amount of missing data. It did this by assuming that data was missing at random.

If there is a true link between adverse events in childhood and premature death, the reasons for this remain unknown. The researchers suggest that childhood exposure to adverse experiences could affect brain or other biological system development. Or, they suggest, it could encourage behaviours which reduce stress in the short-term but increase mortality in the long-term. However, this is speculative.

It is possible that the study has not been able to fully account for all health-related or environmental factors that could be associated with both adverse events and premature death, and it could be these that influence the relationship.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Summary

“Traumatic childhoods increase the risk of death before the age of 50 by up to 80%,” reports the Mail Online. The news is based on research that followed children born during one week in 1958.

Links to Headlines

• Traumatic childhoods increase the risk of death before the age of 50 by up to 80%, claims study. Mail Online, September 9 2013

Links to Science

• Kelly-Irving K, et al. Adverse childhood experiences and premature all-cause mortality. European Journal of Epidemiology. Published online July 2013

Editor’s Note: *clarification provided for our US readers.