Maternal physiological changes in pregnancy range of effects during the pregnancy. Pregnant women experience numerous adjustments in their endocrine system that help support the developing fetus. The fetal-placental unit secretes steroid hormones and proteins that alter the function of various maternal endocrine glands. Sometimes, the changes in certain hormone levels and their effects on their target organs can lead to gestational diabetes and gestational hypertension. Levels of progesterone and estrogen rise continually throughout pregnancy, suppressing the hypothalamic axis and subsequently the menstrual cycle. The progesterone is first produced by the corpus luteum and then by the placenta in the second trimester. Women also experience increased
Menstrual cycle half months postpartum. There is a wide range of response among individual breastfeeding women, however, with some experiencing return of menstruation at two months and others remaining amenorrheic for up to 42 months postpartum. The word "menstruation" is etymologically related to "moon". The terms "menstruation" and "menses" are derived from the Latin "mensis" (month), which in turn relates to the Greek "mene" (moon) and to the roots of the English words "month" and "moon". Even though the average length of the human menstrual cycle is similar to that of the lunar cycle, in modern humans there is no relation between