Postpartum depression affects a significant proportion of women after they have had a baby. It usually develops in the first four to six weeks after childbirth, although in some cases it may not develop until several months later.
Symptoms include low mood, fatigue, anxiety, irritability, feeling unable to cope, and difficulty sleeping, but it often is undetected and commonly underdiagnosed.
The researchers, led by Dr. Rebecca Mercier of the University of North Carolina, asked 688 women who were 15 to 19 weeks pregnant and attending a pregnancy clinic whether they were having an “intended,” “mistimed,” or “unwanted” pregnancy. About two-thirds (64 percent) of the pregnancies were intended, 30 percent were mistimed, and six percent were unwanted. The mistimed and unwanted pregnancies were categorized as unintended for purposes of analysis.
When the babies were three months old, 11 percent of the mothers with unintended pregnancies had postpartum depression, defined as a score of greater than 13 on the Edinburgh Postpartum Depression Scale. The rate in the intended group was five percent.
After a year, 550 women were followed up on. In the unintended group, 12 percent had postpartum depression compared with three percent of the intended group. This equates to 2.1 times the risk at three months, and 3.6 times the risk after a year.
“Once many risk factors such as age, poverty, and education level were taken into account, women with unintended pregnancies were twice as likely to have postpartum depression after a year,” researchers said.
Full results are published in BJOG: An International Journal of Obstetrics and Gynaecology. The team concluded, “While many elements may contribute to postpartum depression, unintended pregnancy could also be a contributing factor.”
“Unintended pregnancy carried to term may have a long-term effect on women,” Mercier said. “Health care professionals should therefore consider asking about pregnancy at early visits, as women who report that their pregnancy was unintended or unwanted may benefit from earlier or more targeted screening both during and following pregnancy.”
Louise Silverton, M.Sc., of the London-based Royal College of Midwives, commented that the research points at the importance of access to midwives. “The consequences of this can be serious, for women, for families, and for the health service.”
Postpartum depression is distinct from the so-called “baby blues,” which is a transitory state of tearfulness suffered by about half of postnatal women within about three to four days of birth.
It has long been believed that postpartum depression is linked to changes in hormone levels during and shortly after pregnancy, but this idea is disputed by some experts.
Other possible triggers, aside from unplanned pregnancy, include inability to breastfeed (if it was hoped for), a history of depression, abuse, or mental illness, smoking or alcohol use, fears over child care, anxiety before or during pregnancy, background stress, a poor marital relationship, a lack of financial resources, the infant’s temperament or health problems such as colic, and especially lack of social support. A difficult or preterm birth or low birthweight also can contribute.
Genes may also play a role in predisposing women to postpartum depression. Furthermore, sleep, or lack thereof, often has been put forward as a possible trigger for postpartum depression.
Other studies point to a link between postpartum depression and diet. Omega-3 fatty acids have received the most attention. Numerous studies have found a positive association between low omega-3 levels and a higher incidence of postpartum depression.
Overall, the factors that put women at higher risk for postnatal depression are similar to those that put people at higher risk for depression at other times in their lives. Despite all of the research, postpartum depression can start for no obvious reason, and conversely, a woman with many risk factors may not develop postpartum depression.
Writing in BJOG: An International Journal of Obstetrics & Gynaecology, one of the authors of the unintended pregnancy paper, Dr. John Thorp of UNC, said, “The perinatal period is a highly vulnerable time for the development or exacerbation of psychiatric illness, including both depression and anxiety disorders.”
He calls for assessment of trauma history and post traumatic stress disorder to be measured using brief questionnaires in primary care settings, “in addition to the depression assessment that is becoming a standard of care.”
Mercier, R.J., Garrett, J., Thorp, J., & Siega-Riz, A.M. Pregnancy intention and postpartum depression: secondary data analysis from a prospective cohort. BJOG An International Journal of Obstetrics and Gynaecology. 8 May 2013 doi:10.1111/1471-0528.12255
Meltzer-Brody, S. and Thorp, J. The contribution of psychiatric illness on perinatal outcomes. BJOG An International Journal of Obstetrics and Gynaecology. 27 July 2011 doi: 10.1111/j.1471-0528.2011.03072
Depressed mother holding her infant photo by shutterstock.