||WARNING: Be aware that the following information describes rare complications and surgical procedures that some readers may find disturbing. You may choose not to read all or parts of this section.
Using a stitch in the cervix
A very rare complication that can happen during the middle phase of pregnancy (or the 2nd trimester) involves the woman's cervix spontaneously and painlessly opening, usually very rapidly and unpredictably, with minimal or no uterine contractions. This leads to a late miscarriage, if the pregnancy is between 12 to 20 weeks (as classified in Australia), or a very premature birth if the pregnancy is between 20 to 28 weeks (occasionally it can occur as late as the first few weeks of the 3rd trimester, up to 32 weeks). The medical term for this complication is 'cervical incompetence' or the woman having an 'incompetent cervix' (not a very desirable description). It is thought that 20 - 25 % of babies born between 12 and 28 weeks do so because of this condition.
The cause of cervical incompetence is not fully understood, but it is believed to be due to a physical weakness in the woman's cervix that makes it susceptible to 'giving way' as the baby becomes larger and heavier, placing increased pressure on the cervix as the pregnancy progresses. Even though the 'condition' has been described as early as the 17th century, accurate diagnosis in any individual woman is difficult because there are no well-defined or strict criteria to definitely say that a woman has an 'incompetent cervix'. This poses a dilemma for caregivers because in most cases, the condition is only identified in retrospect, after one (or more) of the woman's babies has been born in this manner.
Some other health aspects that are thought to be associated with an increased likelihood for a woman's cervix to respond in this way during pregnancy include: