To become board-certified in Obstetrics and Gynecology, you have to take a big written multiple-choice test, and then two years into practice, submit a list of all your surgeries and 40 of your office patients' case histories (names removed, of course) to the American Board of Obstetrics and Gynecology for an oral examination. I was helping one of my ex-residents get ready for her orals, and I saw a case on her list that made me think.

A patient came to her for genetic counseling before getting pregnant. The patient had a disease called cystic fibrosis (CF), a serious lung disease that, among other things, typically requires multiple hospital admissions and leads to a shortened life expectancy. CF is transmitted genetically in a recessive fashion: the patient has two genes for the condition, and no healthy genes to dominate the other two. People of European ancestry have about a four percent chance of carrying one bad copy of the gene. If her husband had two normal genes, like 96% of the population, their children could only be carriers of the trait, and wouldn't have the disease. But her husband was tested and found to be a carrier. This meant that (statistically speaking) 50 percent of their children would have this life-threatening condition. Because they knew so well how difficult CF could be, they really wanted to avoid having a baby with cystic fibrosis. Luckily, they found out that he was a carrier before they had any children together.

So then what? In this case, they planned to use a very high-tech option, in vitro (IVF), to make several embryos, and then test the embryos before they are placed into the woman's uterus. This is called pre-implantation genetic diagnosis, which prevents the mother from conceiving a baby with a detectable genetic condition. It is an expensive option, but having CF is terribly expensive too. Not to mention the emotional costs of watching your child suffer.

This case made me think again about the importance of seeing the doctor or midwife before becoming pregnant, so you can be screened for factors that might indicate risks to your future babies. For more information, see my article on drspock.com, Before You Are Pregnant: The Pre-Conception Visit.