Changes of the female reproductive system during pregnancy

During pregnancy, there are noticeable changes taking place in the organs of the reproductive system influenced by hormones (estrogen and progesterone). The followings are some of the basic changes caused by these hormones in the women's body (organs) during pregnancy.

Uterus

Hence, there are changes in the different structure of the uterus increasing it to five times its normal size in length, depth, width, thickness and weight:

• Length: from 6.5 to 32 cm.
  
• Depth: from 2.5 to 22 cm.
  
• Width: from 4 to 24 cm.
  
• Weight: from 50 to 1000 gr.
  
• Thickness: from 1 to 0.5 cm.

Also, the capacity of the uterus expands to accommodate normally a seven-pound foetus and the placenta, the umbilical cord, 500 to 1000 ml of amniotic fluid, and the foetal membranes. During pregnancy, the abdominal contents are displaced to the sides as the uterus grows, which allows ample space for the uterus within the abdominal cavity. Also, note the following changes taking place with uterus during the gestational period.

• The growth of the uterus occurs at a steady and predictable pace.
  
• Measurement of the fundal height is important to note and record during pregnancy as it increases in size.
  
• Make note of the growth/changes that occur too fast or too slow as it could be an indication of problems with the pregnancy.
  
• The size of the uterus typically reaches its peak at 38 weeks of gestation (see figure 4.1. below). At this time, the uterine fundus may drop slightly as the foetal head progress down into the pelvis for delivery referred to as lightning. Lightning is more noticeable in a primigravida than the multipara.
  

(Remember that a primigravida is a woman pregnant for the first time while a multigravida or multipara is a woman who has been pregnant more than once).

During pregnancy, the amount of estrogen produced is more than the level released the entire life of the women. Oestrogen enhances maternal blood flow to the uterus and the placenta ensuring the supply of nutrients and oxygen to the growing foetus. In a similar manner, the waste products from the foetus are removed to the mother's blood.

With the same token, the progesterone level is also very high during pregnancy causing, among other things, the woman's internal structures to increase in size, including the uterus, enabling it to accommodate a full-term baby. Progesterone has other effects on the blood vessels and joints, which we will discuss later in this study session.

Cervix: the cervix can be considered as an external door of the uterus. It undergoes a marked softening. "A mucus plug, which is known as "operculum" is formed in the cervical canal during pregnancy as a result of enlarged and active mucous glands of the cervix. Its function is to seal the uterus to protect the foetus and the foetal membrane from infection. The mucus plug is expelled at the end of the pregnancy usually at the onset of labor or preceding it by a few days named "show". The mucus plug is called "bloody show" when tingled with blood. Just prior to the beginning of labor, there will be additional changes and softening of the cervix so that it relaxes more to allow the fetus to pass through.

Vagina: one of the changes observed with vagina starting early pregnancy is that its colour changes from normal light pink to a purple type colour due to the increased circulation.

Ovaries: during pregnancy, the follicle-stimulating hormone (the FSH), which prevents ovulation and menstruation, ceases its activity due to the increased levels of oestrogen and progesterone secreted by the ovaries and the corpus luteum. Until about 10 to 12 weeks, the corpus luteum goes on producing the hormones, the time when the placenta matures and overtakes the production of oestrogen and progesterone hormones in adequate amount. Then, the corpus luteum gradually decreases in size although it continues functioning in small scale.