I am 18 weeks pregnant, and so far, it's been a pretty stressful pregnancy. I'm wondering, can exteme stress cause birth defects?
To answer the basic question: emotional stress in itself probably doesn't cause birth defects, but it is hard to study scientifically. In theory, emotional stress could have a direct effect on a pregnancy due to higher-than-normal circulating levels of corticosteroid hormones. Corticosteroids have many biological effects. But to date, no one has shown an increase in birth defects directly attributable to the mom's emotions during pregnancy.
Emotional stress may be associated with preterm birth or poor fetal growth, but even that relationship is uncertain. When scientific studies try to answer these questions, the effects of stress have to be separated from other risk factors including how the person deals with the stress. Cigarette smoking or alcohol use, for instance, can lead to poor pregnancy outcomes. If a mom is getting beaten by her partner, trauma to her abdomen is dangerous to her and to the developing fetus. Even gaining too much weight or too little can lead to pregnancy complications. So it is difficult to determine the direct effects of emotions on the pregnancy.
Keeping safe and taking good care of yourself during difficult times can help to offset the possibility of risk to the pregnancy from severe stress.