37 weeks.

The baby weighs about 6 1/2 pounds and is considered full term. Now he can be born at any time, although most first-time pregnancies are late.
Now is when to expect lightening, the baby getting ready to "drop" into position for the birth. This is important because although it lowers my center of gravity, it lessens the pressure on my diaphragm and I can breathe more easily.

The APA's information is: The amount of amniotic fluid begins to decline around 37 weeks. Braxton Hicks contractions also increase in frequency.