The exact cause of labor starting is still not fully understood, but it's believed to be a complex interplay of various factors, both hormonal and physical.
Hormonal Factors:
- Progesterone: This hormone is responsible for maintaining pregnancy, and its levels decrease as the due date approaches. This drop in progesterone triggers the release of other hormones.
- Estrogen: Estrogen levels rise in the final weeks of pregnancy, preparing the body for labor.
- Prostaglandins: These hormones help soften and dilate the cervix. They are released by the uterus and the placenta.
- Oxytocin: This hormone is known as the "love hormone" but plays a crucial role in labor. It stimulates uterine contractions and helps the cervix dilate.
Physical Factors:
- Uterine Stretching: As the baby grows, the uterus stretches, which can trigger labor.
- Cervical Ripening: The cervix softens and thins in preparation for labor.
- Fetal Hormones: The baby's adrenal glands release hormones that trigger labor.
- Placental Aging: The placenta starts to age and function less effectively towards the end of pregnancy, leading to labor.
Other Factors:
- Stress: While not a direct cause, stress can trigger labor in some women.
- Sexual Activity: Orgasm can release oxytocin, which may help stimulate labor.
- Membrane Rupture: When the amniotic sac breaks, it can trigger labor.
It's important to remember that every pregnancy is different, and there's no single answer to the question of what causes labor to start.
