Abnormalities Of The Pelvis In Birth

A woman’s body, or at any rate her pelvic organs, are designed to give birth. The normal, healthy female pelvis can easily accommodate a growing foetus and give birth to it safely. As mentioned above, in the past, and in some Third World countries today, many women were malnourished and suffered from rickets in childhood, as a result of which several bones were soft and deformed. They were smaller on average than modern women with consequently smaller and sometimes malformed pelvises – hence the problems at childbirth.

Today it is rare for a woman’s pelvis to be deformed or too small for a normal delivery. Sometimes however she is extremely short, and her baby is a bit too big for her pelvis. Diabetic women, although they have pelvises of normal proportions, may also occasionally run into problems because their babies tend to be bigger than average. This discrepancy between the size of the baby’s head and that of the mother’s pelvis is known as disproportion.

If a pregnant woman has already had at least one normal delivery, disproportion is rarely a problem. For first-time mothers, an internal examination of the pelvis early in pregnancy may reveal possible aberration. Sometimes, although there is no hint of trouble early on, the baby’s head fails to engage (move down into the cavity of the pelvis) in the last few weeks. A second internal examination is then performed and, if disproportion is positively demonstrated, a Caesarean section will probably be necessary.

Sometimes disproportion may be more apparent than real because the baby’s head is poorly flexed, with its chin not touching its chest. Once the head does flex – usually during the first stage of labour – the disproportion disappears and it can be born normally. However in cases of true disproportion the baby must be delivered by Caesarian section.