I am 34 years old and seven weeks pregnant with my second child. My first child was born healthy at almost nine pounds. I just found out that my husband's parents are first cousins. From talking to people, including my doctor, I have learned that this fact increases the chances of birth defects in our children. I am glad there are tests that can detect if there are any potential problems with the child I am carrying now, but I would like to be as informed as possible, about how the fact that my in-laws are related might affect my unborn child.
The problem with close relatives is that if there's a recessive gene that otherwise wouldn't have a chance of combining with the same recessive gene in the general population, that gene has a better chance of combining when mixed with the same "gene pool." If there are no devastating recessive genes (like Sickle Cell, metabolism defects, etc.), the biggest worries are things like being color-blind, and prone to hypertension or breast cancer. More than likely, the odds are in your favor, but a "pedigree" determined by a geneticist could help allay your worries.