One of the most exciting areas of research into pregnancy complications in recent years has to do with the Maternal-Fetal Conflict. First proposed by David Haig, it has to do with the idea that mother and child have different survival needs.
|Picture taken from Wikipedia|
From a purely biological perspective, the goal of reproduction is to pass on your genetic material. For the father, and therefore the placenta, the bigger the baby, the better the chances of survival. As far as the placenta is concerned, a 100 pound baby sounds awesome. Thus, the placenta digs deep into the uterus, shunting crucial nutrients and oxygen from the mother's blood supply to the baby.
The mother, on the other hand, wants a baby big enough to survive BUT small enough to fit through the birth canal so that she, too, can survive to reproduce again. Our bodies are amazing and can expand to birth an 8, 10, even 12 pound baby. But let's face it--a 100 pound baby simply isn't going to fit. Thus, the mother must limit the placenta in some way to ensure her own survival. The mother's immune system attacks the placenta as a foreign invader, preventing it from attaching too well and from comandeering too many nutrients.
It's a very delicate balance to grow a baby that is big enough but not too big. Dr. Haig suggests a normal pregnancy is like a tug of war: both sides are pulling on the rope, but the ribbon in the middle doesn't move if each side pulls equally. However, if one side starts to win the tug of war, if the survival of the other side is threatened, it will employ strategies to keep itself safe. He theorized that the fetus must be sending some signal to the mother that triggers the cascade of symptoms known as preeclampsia. This theory was confirmed by another doctor, kidney specialist Ananth Karumanchi, who discovered elevated levels of a protein called sFlt1 in women with preeclampsia.
Tomorrow I plan to explore the role of sFlt1 in preeclampsia.