Study suggests two children may be best for women’s mental health

A recent study published in the Journal of Affective Disorders suggests that having children may offer some protection against bipolar disorder and major depression in women. Researchers analyzed data from a large sample of women in the United Kingdom and found that those who had given birth were less likely to experience these mental health conditions compared to those who had not. The findings also indicate that having two children might be associated with the lowest risk of these disorders.

The researchers at Soochow University were motivated to conduct this study because of two significant trends in global health. First, birth rates are declining in many countries around the world. At the same time, mental health disorders, including bipolar disorder and major depression, are becoming more common. Scientists know that having children can have a significant impact on a woman’s body and mind. There are physical changes during pregnancy and after childbirth, and there can be emotional and social shifts as well.

However, there is not much research looking specifically at how having children relates to the risk of bipolar disorder and major depression in women. Understanding this relationship is important, especially as societies grapple with both falling birth rates and rising rates of mental illness. The researchers wanted to provide better information to women making decisions about family planning, in light of these dual challenges.

To explore this issue, the researchers used data from a large project called the UK Biobank, a collection of health information from about half a million people living in the United Kingdom. The data was gathered between 2006 and 2010. Participants in the Biobank, who were between 37 and 73 years old at the time of enrollment, completed detailed questionnaires and underwent health assessments.

For this particular study, the researchers focused on women in the Biobank. They started with data from over 273,000 women. However, to get a clear picture, they needed to remove some participants. They excluded women who did not have information about bipolar disorder or major depression, and women who did not have information about the number of children they had given birth to. After these exclusions, the study group included just over 55,700 women.

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The key piece of information the researchers looked at was the number of live births each woman reported. This information came from a touchscreen questionnaire where women were asked directly, “How many children have you given birth to? (Please include live births only)”. The women entered a number or chose “Prefer not to answer”.

The researchers then looked at whether each woman had been diagnosed with bipolar disorder or major depression. This information was gathered when the women joined the Biobank using a standard psychological questionnaire and interviews with trained staff. The diagnoses were based on established guidelines used by doctors and mental health professionals.

After analyzing all the data, the researchers found a significant association between having live births and a lower risk of bipolar disorder and major depression. When they compared women who had given birth to women who had not, they discovered that women with a history of live births had a considerably lower chance of having these mental health conditions.

Specifically, they estimated that the risk was about 30% lower in women who had given birth. The researchers also investigated if there was a relationship between the number of live births and mental health risk. They found a non-linear pattern. As the number of live births increased from zero to two, the risk of bipolar disorder and major depression decreased. However, beyond two live births, the protective effect appeared to plateau, and having additional children did not further lower the risk.

In fact, having more than two children did not provide additional mental health benefits. In some analyses, the risk appeared to increase slightly, but this finding was not statistically significant. This suggests that having two children may be associated with the lowest risk of bipolar disorder and major depression for women.

Interestingly, when the researchers looked at specific subgroups of women, they found some variations. For example, in women who had experienced certain types of miscarriages or induced abortions, and in women who did not use oral contraceptives, the protective effect of live births was not as clear, or even reversed in some cases. However, in most of the subgroups analyzed, the overall finding that live births are linked to a lower risk of bipolar disorder and major depression held true.

The researchers controlled for a range of other factors that could influence mental health. These included things like age, education level, income, ethnicity, where they lived, and employment status. They also considered lifestyle factors such as body mass index, smoking habits, alcohol intake, and physical activity levels. Finally, they included clinical factors such as whether the women had been diagnosed with conditions like high blood pressure, diabetes, or cancer.

They also took into account factors related to women’s reproductive health, such as whether they had ever had an abortion, used birth control pills, the age they started menstruating, whether they had used hormone replacement therapy, or had their ovaries removed.

But there are still limitations to consider. Because the researchers used data collected at one point in time, they cannot definitively say that having children causes a lower risk of mental illness. While the researchers considered many factors that could influence the results, it is always possible that other unmeasured factors, such as the level of support women receive from their families or their genetic predisposition to mental illness, could also be important. In addition, the study participants were all from the UK Biobank, and most were of European descent. This means the findings might not be exactly the same for women in other parts of the world or from different ethnic backgrounds.

For future research, the scientists suggest that long-term studies tracking women over time would provide a clearer understanding of how childbirth affects mental health. More research is also needed to explore the reasons behind the link they observed, including the biological, psychological, and social factors that might be involved.

The study, “Having two children might be best for women’s mental health: Evidence from UK Biobank,” was authored by Jingfang Liu, Hao Sun, Ke Zhang, Ibrar Hussain, Yuying Wang, Hongpeng Sun, and Zaixiang Tang.