What causes postpartum depression?

Doctors now believe that postpartum depression (an acute form of depression occurring in women after giving birth) may be triggered by low levels of the hormone progesterone.

Progesterone hormone levels swing hugely during and after pregnancy, which has led some health professionals to hypothesize that this may be a key part of the intense depression suffered by many women after pregnancy. As many as thirty percent of women report the so-called “maternity blues” in the days following pregnancy.

The “maternity blues” are an assortment of symptoms endured in the week (or longer) following delivery, including acute sadness, insomnia, difficulty concentrating, irritability, headaches, and bouts of tears. Women generally experience the strongest symptoms four to five days after giving birth, which is when hormonal fluctuations are at their acute. These feelings may develop into more chronic and longer-lasting postpartum depression.

A trial carried out by Harris et al. tracked 156 women experiencing their first pregnancy. The investigators noted the patients’ progesterone levels at several points during the pregnancy and after birth, and evaluated their feelings according to “the Edinburgh postnatal depression scale, the Stein scale for maternity blues, and the Beck depression rating inventory.”

Progesterone levels were measured in the patients by collecting saliva samples daily in the weeks before delivery, and for the following 40 days. The women were also asked to complete a daily questionnaire to gauge mood after birth for 10 days, and after 40 days they were seen by a psychiatrist to assess depression. Blood samples were also drawn at four separate points during the trial.

In all women, progesterone production builds slowly during pregnancy, when it is chiefly produced by the placenta. By the time of birth, progesterone levels are several hundred over normal. After birth and the shedding of the placenta, progesterone levels decline rapidly and considerably.

Most of the patients participating in the trial experienced at least some of the symptoms of the maternity blues in the week following giving birth. However, the investigation concluded that the women most likely to suffer from the maternal blues were those with the most dramatic changes in progesterone levels, e.g., the highest levels of progesterone during pregnancy, the most dramatic drop in levels after birth, and continued lower progesterone levels postpartum.

Women close to giving birth or already experiencing the “maternity blues” may want to discuss progesterone therapy with their doctors as a means of controlling their depression.

Sources: B Harris, L Lovett, R G Newcombe, G F Read, R Walker, D Riad-Fahmy. “Maternity blues and major endocrine changes: Cardiff puerperal mood and hormone study II.” BMJ 1994;308:949-953 (9 April).