CHAPTEK V 



PARTURITION— PUERPERIUM— LACTATION 



During the later stages of pregnancy, and more particularly 

 in the final week or two, the uterus shows an increasing irrita- 

 bility, which displays itself in more powerful contractions, giving 

 rise to pains. With the near approach of actual labour, the 

 foetal membranes distended with fluid are forced into the cervix 

 uteri, which becomes dilated, and small vessels become torn, 

 and some blood is discharged through the genital passages. 

 Next, the longitudinal muscles of the uterus contract and cause 

 the external os to open. The contraction of these muscles may 

 be said to mark the beginning of the actual labour pains and to 

 constitute the first stage in parturition. The body of the uterus, 

 the cervix, and the os then form a continuous passage. Typically 

 the membranes rupture at this time, but this process may begin 

 a little earlier or be deferred to slightly later. (Occasionally 

 the membranes remain umuptured till after birth, the child 

 being born inside its " caul " or " water-bag.") The amniotic 

 fluid commences to escape, but only a portion of it. In a normal 

 presentation the head of the foetus comes down into the cervix 

 and closes the external os. This marks the termination of the 

 first stage of labour. 



The uterine muscles again contract forcibly, and not merely 

 the longitudinal muscles, but also the circular muscles as well 

 as those of the abdominal wall and the diaphragm. These con- 

 tractions expel the foetus from the uterus to the vagina and 

 thence to the exterior, the final propulsion being due chiefly 

 to the contractions of the abdominal muscles. The vagina is 

 very yielding, and the passage of the foetus through it is facilitated 

 further by a copious secretion of mucus. The perineum yields 

 by stretching as the foetal head passes out, but it is often torn 

 considerably, and the torn edges may have to be stitched together 

 after parturition is over. What is left of the hymen is usually 



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