Depression can seriously decrease female fertility. New research reveals that postnatal depression, defined as experiencing depressive episodes within 12 months of giving birth, significantly lowers women's chances of having more than two kids. In fact, the effect of postnatal depression was just as strong as that of major birth complications in lowering female fertility after the birth of the second child, according to researchers.
"Having a bout of postnatal depression at both first and second birth had the second largest effect size on progression from parity 2, smaller yet within the range of major birth complications," said lead researcher Sarah Myers and her team at the University of Kent's School of Anthropology and Conservation.
Previous studies reveal that postnatal depression often hinders cognitive, emotional, physical and social development in kids because of its negative influence over critical interactions between mother and baby.
Researchers said the latest study is important because it is one of few to shed light on how postnatal depression influences future fertility of women.
The latest study involved survey data from over 300 women. Researchers said that all mothers were born between 1930 and 1967 and lived in industrial western countries while raising their children.
"A survey was designed to gather complete reproductive histories and retrospective measures of PND to measure the effects of PND on fitness. Respondents were born between 1930 and 1967, with the majority based in the UK during their childrearing years," wrote Myers and her team.
"The hypothesis that PND is detrimental to fitness is assessed using Mann-Whitney U tests on completed fertility. Binary logistic regression modeling is used to test the hypothesis that PND reduces the likelihood of parity progression," they added.
Study results revealed that mothers who have suffered postnatal depression experienced significantly lower fertility levels compared to those who have never suffered postnatal depression. The study also revealed that this was particularly true in women who suffered postnatal depression after their first child.
While experiencing higher levels of emotional distress during first postnatal period decreased women's chances of having a third child, it did not influence women's likelihood of having a second child.
"Our results call into question adaptationist arguments, contribute to the growing understanding of the importance of emotional wellbeing to fertility decision making, and given the economic consequences of markedly below replacement fertility, highlight a potential new source of financial incentive to invest in screening and preventative measures to ensure good maternal mental health," researchers wrote.
The findings are published in the journal Evolution, Medicine and Public Health.