Pregnancy

The physiology of pregnancy really fascinates me. I've heard somewhere the strange comparison between a fetus and a parasite. And no matter how distasteful this analogy is, it's an interesting idea. The embryo or fetus siphons away nutrients from the mother, and the placenta secretes various hormones that favor the developing organism at the expense of maternal health. Indeed, if something goes wrong, there can be drastic adverse consequences for the mother: ectopic pregnancy outside the uterus, molar pregnancy as cancerous growth, placenta previa or accreta causing life-threatening hemorrhage. To me, it seems like a scary risk for such a normal process.

But even in the progress of normal pregnancy, the mother is at risk for developing gestational diabetes because of placenta-induced insulin resistance, pre-eclampsia leading to stroke or seizure, pulmonary embolism causing death. Not to mention all the less severe but annoying symptoms like morning sickness or lower back pain or stretch marks. The incidence of domestic violence increases in pregnancy (paradoxical? it certainly doesn't favor the species). Even after the baby is delivered, mothers may suffer from postpartum depression, or worse, psychosis.

Ignoring all the things that can go wrong, the physiology of pregnancy is still an astounding feat. The mother - and her heart, lungs, kidneys - accommodate for a 5L intraabdominal mass. Tidal volumes are increased 40%, cardiac output 30-50%, GFR 50%. That's significant. Pregnancy is really a unique and impressive physiologic state.

Where's the guy in all this? (Well, males do produce a tremendous amount of sperm - ~1000/heartbeat, but still, I don't think it quite compares).