Women who give birth to baby boys are more likely to experience postnatal depression, according to new research.
The study, published in the journal Social Science and Medicine,found that mums who welcomed boys were 71-79 per cent more likely to develop PND compared to those who gave birth to baby girls. In addition, women who experienced difficult births were 174 per cent more likely to experience PND compared to women who had no complications during their delivery.
And inflammation may well explain the link.
"PND is a condition that is avoidable, and it has been shown that giving women at risk extra help and support can make it less likely to develop," said lead author Dr Sarah Johns. "The finding that having a baby boy or a difficult birth increases a woman's risk gives health practitioners two new and easy ways to identify women who would particularly benefit from additional support in the first few weeks and months."
With previous research highlighting an association between inflammatory immune response and depression, (it has been suggested that depressive symptoms are an evolutionary adaptation to both prevent and fight infection) Dr Johns and her colleague Dr Sarah Myers decided to examine whether there was a link between the sex of infants and PND. Why? Because being pregnant with a male baby has previously been associated with increased inflammation. Analysis of placental tissue also indicates that mums produce a stronger inflammatory response to boy babies.
As part of the study, the researchers looked at the complete reproductive histories of 296 women with 651 births between them. Women self-reported whether they received a diagnosis of PND, the sex of their baby and whether they experienced any complications during their delivery. They also noted how long their recovery from the birth complications took.
When the authors analysed the results, as well as finding an increased risk of being diagnosed with PND after having baby boys or experiencing a difficult birth, they made a number of other interesting observations. The odds of PND increased by 166 per cent when mothers gave birth to baby boys from complicated births. Additionally - and perhaps unsurprisingly - having a complicated birth which required an extended recovery time increased the odds of PND by 151–168 per cent.
The researchers note that their findings support adding PND to the list of perinatal conditions for which baby boys pose increased risk. (Male babies also increase the odds of mums experiencing pre-eclampsia, as well as gestational diabetes.) They also argue that if "foetal sex-related inflammation" does underlie the results, the risk of antenatal depression during pregnancy is likely to be similarly increased by male bubs, something they say requires further research.
But while inflammation could be a factor, what else might explain the link between having a baby boy and an increased risk of PND?
According to the authors, an "undocumented preference for daughters" in the women they studied is one such possibly - in other words: gender disappointment. "A neat way for future research to tease apart the potential roles of inflammation caused by a male foetus, versus psychosocial stress related to a preference for daughters, would be to assess whether foetal sex predicts antenatal depression in mothers who do not know the sex of their unborn infant," they write.
Clinical Psychologist and director of the Centre of Perinatal Excellence, Dr Nicole Highet agrees that gender disappointment may play a role in the link between PND and increased rates of postnatal depression. "Certainly parents can experience gender disappointment," she says, "when they have high hopes of a baby of a certain gender. For this reason finding out the sex of their baby during pregnancy (as opposed to at the birth) can give parents more time to come to terms with the gender of the baby prior to his or her arrival – which brings with it a range of other physical, emotional and psychological adjustments."
But Dr Highet says it's important to note that while there may be some link between women specifically being more disappointed at not having a girl, there are cases where both men and women experience gender disappointment, "particularly if they already have other children of one gender and decide to have another child in the hope of the other – whether it is for a boy or a girl."
According to Dr Highet, the study's findings also confirm what we know about the association between birth complications and PND. "We know that women who experience complications when things don't go to plan during birth can be left with a range of emotional and mental health challenges including, distress, grief, disappointment, feelings of failure and potentially post-traumatic stress disorder," she says. " It is therefore important that women (and men) as well as health professionals acknowledge and recognise the impacts of birth and actively take steps to help them to recover from a traumatic birth and thereby reduce the likelihood and incidence of PND."
She notes that the research also highlights the importance of screening and assessment to identify women who are more likely to develop emotional and mental health problems, providing women and health professionals alike with the opportunity to be more aware and provide additional support to prevent the incidence of PND.
"With having a personal history of mental health problems being amongst the most influential causal factors of antenatal and postnatal depression and anxiety, the study highlights how early detection can help prevent such conditions occurring, or promote early intervention," Dr Highet says.
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