Relying on fundal height as above must take into account any explainable discrepancies. For instance, a third trimester baby who has "dropped" between the last visit and the current one may show a fundal height less than last visit! The lower baby means the top of the uterus is lower, measuring less from the immovable pubic bone than the previous time. A simple pelvic exam can determine the descent of the baby's head into the maternal pelvis to explain this. If a baby's turned sideways, as often occurs in the second trimester, the fundal height can be unusually short for what's expected, since the greatest dimension then lies across the horizontal. A breech baby, usually sitting up high in the uterus, will yield a larger fundal height. These are all circumstances that can defuse concerns over abnormal fundal heights, so it's obvious that it wouldn't be a good idea to revise a due date based on a fundal height. (Then again, the fundal height may be just the thing to provoke investigation leading to a diagnosis of breech.)
Because the weight of your occupied uterus can press on the Vena Cava to obstruct blood flow (drainage) back up to the heart, this obstruction backs up the works. When the fluids of your lower body can't equilibrate with the fluids in your upper body, the bottom half becomes overhydrated. You see this as swollen ankles. The swelling can also be fairly high up, even involving your wrists, giving you the false carpal tunnel syndrome with tingling of your fingers.
Edema is normal, but it can also accompany pre-eclampsia. But swelling in the absence of hypertension, spilling protein, and jumpy reflexes is merely one of the Middle Miseries of Pregnancy. It can continue and worsen, blossoming into a third trimester misery as well.
FHR (Fetal Heart Rate)
Many people think that a baby's blood circulation is directly connected to the mother's circulation. This is a myth. Many think that you can tell the gender of your baby by the count of the fetal heart rate per minute. Another myth.
The very fact that your own heart rate and your baby's heart rate are different is the proof that they're not connected. If they were, such opposing pulsatile forces would create a midpoint of turbulence, perhaps creating hemorrhoids for you the size of the wheelbarrow they'd have to be carried in.