Physiological Changes

In early pregnancy, human chorionic gonadotrophin is secreted by the embryo and placenta, and stimulates the production of oestrogen and progesterone by the mother's ovary (corpus luteum - See Gynaesurgeon.co.uk - Fertility) until around the 10th week of pregnancy when the placenta takes over. These hormones are responsible for many of the physiological changes in the mother. The first change of note is a missed period because ovulation stops. There is a change in the normal rhythmic activity of the uterine muscle with longer resting phases, under the influence of progesterone, while the womb (uterus - See Gynaesurgeon.co.uk - Anatomy & Physiology) enlarges as a result of the increasing oestrogen secretion. If there is bleeding after a missed period advice should be sought from your doctor. (See Early Pregnancy Problems)

During pregnancy the placenta, fetus and sac secrete several steroid and protein hormones and growth factors, so that the mother's body will adapt for pregnancy. The hormones produced include oestrogen, progesterone, human chorionic gonadotrophin (HCG), human chorionic somato-mammotrophin (HCS), and placental adrenocorticotrophic hormone (PAH). There are also specific growth factors secreted, such as the inhibins, and insulin-like growth factors which are produced by the placenta and the mother's ovaries.

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