Q. The baby of our good friends was born with something called spina bifida: the doctor called it a birth defect. So, does science know when during the birth process birth defects occur? 

A. Spina bifida is classed as a birth defect. The tube that develops into the spine is formed early in gestation and closes about the end of the fourth week. So, a spina bifida birth defect will likely be in place before that. Most of the internal body organs—for example, brain, lungs, heart, kidneys, digestive system—are developed by the end of that first 12 weeks (the 1st trimester) of pregnancy. The brain, however, continues to develop for years after the baby is born.

According to Mayo clinic, there may be some genetic contribution if there is a family history. It’s also likely that epigenetic factors can also increase the risk for spina bifida. For example, a lack of Vitamin B-9, folate, maternal obesity prior to conception, maternal diabetes where the blood sugar is not well controlled during gestation, or even too high a core body temperature from fever or a lot of saunas. Research shows that the impact of epigenetics (including lifestyle) is real. But I hazard to guess that few people think about that. Estimates are that birth defects occur in less than 5% of pregnancies. When they do, however, it can be devastating to all concerned.