Morris - abnormal fetal growth

The factors for abnormal fetal growth; there are many, some of them are intrinsic in that this is something that the mom has. And some of them are related to environmental factors and lifestyle factors that the mom might be involved in. So when we have a major medical condition in the mom, such as hypertension for example or severe chronic respiratory disease, we will have an intrinsic factor in the mom that’s going to lead to difficulties in accommodating the pregnancy and going through all the physiologic changes in the pregnancy. So for example, we are starting to see cystic fibrosis moms get pregnant and they have difficulties with their respiratory function and their gastrointestinal issues in getting enough nutrition. In that setting we can see difficulties with formation of healthy placentas and those babies in those pregnancies are more likely to have intrauterine growth restriction.

The diabetes, it’s an interesting example. If we have a mom with type 1 diabetes, they’re more likely to have; they have a higher incidence of congenital abnormalities in the baby if their glucose control was poor prior to conception. And during pregnancy, they can actually; you can actually see growth restriction if the diabetes is severe enough that it’s affected the microvasculature in their bodies because if it’s affecting it elsewhere in their body it will affect their placental function.

Then you get the type 2 diabetes without vascular disease and they’re feeding the baby too much and getting the macrosomia. In that case the placenta is facilitating the adverse outcome for the baby.  Smoking does result in some vasoconstriction in the placental vessels and leads to decreased perfusion and decreased growth in the baby. One of the really important things we do at the first prenatal visit is to go through mom’s history, identify any existing conditions and if possible diagnose any undiagnosed existing conditions and make sure that they have proper management of their medical conditions to maximize the ability of the placenta to function. The otherwise healthy woman in the absence of infection, usually doesn’t see placental restriction.