Women are more likely than men to suffer from depression, especially during their reproductive years. Rates of depression are higher where stressful circumstances exist such as poverty, lack of education, sexual inequality, poor social support and in pregnancy. Single and adolescent pregnant women are especially at risk.
Pregnancy is a socially and physiologically demanding time and a woman who is just coping with the stresses of life may find the additional burden unmanageable. Mood regulation is modified by sex steroids, specifically the cortisol stress system mediated via the hypothalamic-pituitary-adrenal axis which is overactive in depressed people.
In developed countries, the rate of depression in pregnancy is at least 10% and double that in poorer countries. Irrespective of their socio-economic status, women with affective disorders have a high relapse rate in pregnancy which, in turn, is reflected in poorer maternal and fetal outcomes - mostly early delivery and growth restriction. Again, the common pathway of depression and social adversity is likely to be through the cortisol stress hormone system (O'Keane & Marsh BMJ 2007;334:1003-5).
Given these high rates of occurrence, depression should be specifically enquired about antenatally and actively managed if present. Since two-thirds of women stopping antidepressants during pregnancy will relapse, discontinuation is seldom advisable as the resultant depression can lead to unhealthy behaviours such as smoking, drinking alcohol, substance abuse and poor clinic attendance. About a quarter of those remaining on treatment will relapse, so surveillance levels must remain high.
The teratogenicity of antidepressants has been prominent in the journals recently. Selective serotonin reuptake inhibitors (SSRIs) were introduced in the 1980s as safe mood elevators because of their reasonably rapid onset of action, which is ten days according to the latest reports, plus fewer side effects and lower risk when taken in overdose. Nevertheless, there were incidental reports of birth defects such as nervous system or cardiac abnormalities, and cautions were issued. Now two large studies are reported in NEJM (Louik et al 2007;356:2675-83 and Alwan et al 2007;356:2684-92) which are case-controlled evaluations showing a small absolute risk of SSRIs being causative of defects if taken in the first trimester. These are certainly nothing like the risk posed by thalidomide or isotretinoin. In the US the use of these drugs is increasing and the latest data suggest that 10% of all pregnant women are taking an SSRI (Cooper et al AJOG 2007;196:544-5).
In an editorial, Greene (NEJM 2007;356:2732-3) says it would be pleasing to say there is no risk from SSRIs, but that is not possible. To quote from these major studies, “it is important to keep in perspective that the absolute risks of these rare defects are small” and “the absolute risks associated with SSRIs appear small in comparison with the baseline risks of birth defects that exist in every pregnancy”.
