Women who give birth in winter or spring are less likely than women who deliver in the autumn or summer to suffer from postnatal depression, suggests a US study being presented at a conference.
In addition, those who delivered babies at a higher gestational age were less also likely to develop postnatal depression.
“We wanted to find out whether there are certain factors influencing the risk of developing postpartum depression”
In contrast, women who did not have an anaesthetic during delivery, such as an epidural, had an increased risk of postnatal depression.
The study authors suggested women who did not have anaesthetics may have been at an increased risk, because the pain associated with labour may have been traumatising to them during delivery.
Another reason, they suggested, might be that those who declined anaesthetics just happened to have intrinsic characteristics that made them more vulnerable to experiencing postnatal depression.
The US study authors suggested the protective mechanism seen for women delivering in winter and spring may be due to the enjoyment of indoor activities mothers experience with newborns.
The researchers reviewed the records of 20,169 women who delivered babies from June 2015 to August 2017. A total of 817 – equivalent to 4.1% – women experienced postnatal depression.
Overall, the study authors found Caucasian women had a lower risk of postnatal depression compared to women of other races.
Additionally, increased body mass index was associated with an increased risk of postnatal depression. But there was no association found between depression and mode of delivery.
Lead study author Dr Jie Zhou, from Brigham and Women’s Hospital in Boston, said: “We wanted to find out whether there are certain factors influencing the risk of developing postpartum depression that may be avoided to improve women’s health both physically and mentally.”
While the study did not examine why certain factors might influence the development of postnatal depression, Dr Zhou said the higher the gestational age – the further along a woman was in her pregnancy – the more mature typically the baby will be at delivery.
“It is expected that the mother will do better and be less mentally stressed when delivering a mature, heathy baby,” he noted.
He added: “The significant difference in the risk of developing postpartum depression between Caucasian and other populations may be due to differences in socioeconomic status among these ethnicities.
“Women with increased BMI needed more hospital-based maternal outpatient follow-ups and had more pregnancy-related complications, which could affect maternal outlook,” he said.