Pregnant women face a number of choices. Most are pretty noncontroversial: Don’t smoke or use drugs; avoid raw fish and eggs; get lots of rest. But one dilemma some pregnant women face is less intuitive: whether and how to treat their minds and bodies if they are depressed.

Much attention has focused on postpartum depression (that is, the occurrence of depression in the mother after giving birth), which occurs in about one in 8-10 women. But depression during the nine months of pregnancy occurs as frequently, yet has received less spotlight.

Diagnosing depression in pregnancy can be tricky, as women may initially disregard some of the symptoms, such as changes in mood, appetite or sleep, as normal or to be expected. But here’s what’s critical to know: Identifying and treating maternal depression during pregnancy is particularly important as it impacts not only the mom, but baby as well.

This concept – that maternal mood can be passed on to offspring – is hardly new. It has existed since the days of Hippocrates, and even Shakespeare understood it: In “Henry VI,” a pregnant and despondent Queen Elizabeth laments:

 "Ay, ay, for this I draw in many a tear,  And stop the rising of blood-sucking sighs, Lest with my sighs or tears I blast or drown,  King Edward's fruit, true heir to the English crown." 

Shakespearean insights aside, we now know that chronic depression in pregnancy can alter levels of stress hormones, divert blood (and with it, oxygen and key nutrients) away from the fetus and suppress the immune systems of mother and child, leaving both more vulnerable to infection.