"Due date" is only an estimation; it's an average. When a mother is carrying one baby, the baby is born at 40 weeks, as an average. Even the medical definition of postdates is pregnancy beyond 42 weeks. On the other hand, I didn't find any study regarding the direct relationship between postdates and poor outcomes. As for placenta function, there are babies born early with poor placenta, while there are babies born "late" with healthy placenta. As for astrology signs, the baby will come out when s/he is ready. Best wishes.
When the baby is mature, its digestion system starts to work well and it's normal that the baby has bowel movements (BMs) in utero. How it looks ( color, consistency) in the amniotic fluid tells us how old the poo is. Remember, the amniotic fluid is renewed every several hours. Yes, a whole new bag of water several times a day! That's why it's important to stay hydrated during pregnancy and labor! It's wonderful that your baby had all that BMs after birth. It means it's digestive system is working! It also means the baby is not starving - input /output. Ideally, the baby poo 1x during the first 24 hours, 2x during the second 24 hours, and 3x during the third 24 hours. This mean your baby was ahead of the game! You fed her/him well mm! Good job!