CHAPTER XXIX 

 PREGNANCY. PARTURITION. CHILDBED 



DURING the development of the foetus in the uterus, the 

 following changes occur in the maternal organism : The 

 muscle fibres of the uterus increase in size and number and 

 the whole uterus increases enormously. In the virgin state 

 the uterus is 7 cm long, 3.2 cm broad, and weighs 30 g; at 

 the end of pregnancy it is 37 cm long, 26 cm wide, and 

 weighs about I kg. The intramuscular connective tissue 

 loosens and increases and the blood vessels, nerves, and 

 lymph vessels also increase. The mucous membrane of the 

 uterus thickens and grows over and covers the egg, forming 

 the decidua. That part of the wall of the uterus which 

 grows over the egg is called the decidua reflexa, while the 

 part bordering upon this is called the decidua vera. The 

 placental part of the decidua vera is called the decidua sero- 

 tina. As the uterus increases it fills the pelvic cavity and 

 forces the intestines aside and the diaphragm upward. 

 During pregnancy ovulation and menstruation cease. 



The breasts begin to increase in size during the first 

 months of gestation, the nipple and the areola assume a dark 

 color, the milk glands yield spontaneously or upon pressing 

 a light-colored watery fluid. 



Metabolism is increased during pregnancy. 



The period of gestation reckoned from the day of the last 

 menstruation is about 270-280 days. 



Parturition is effected by the contraction of the muscles 

 of the uterus by which pressure is exerted upon the contents 

 of the uterus. The pressure thus produced may be as much 



324- 



