In our study the multiparas reported significantly
less pain than the primiparas. This may be due to
physical changes in the mother's pelvis resulting from
the first birth, although there is no evidence for such
changes, and to the fact that multiparas generally have
shorter labour.9 Another reason may be the decreased
fear and anxiety in multiparas because they have given
birth before and know what to expect. This is supported
by the observation in our study that the mult-iparas
who "felt prepared by childbirth training" had significantly lower levels of pain.
The positive correlations between several PRI measures
of labour pain and menstrual difficulties are particularly
interesting. There is strong evidence that
women who have dysmenorrhea produce excessive
amounts of prostaglandins, which trigger uterine contractions.25
Drugs that inhibit prostaglandin synthesis
also diminish menstrual pain. Because of the positive
correlation between menstrual and labour pain, it is
conceivable that women who suffer severe labour pain
may also produce excess prostaglandins during labour.
In our study complications during pregnancy were
associated with lower pain scores during labour. This
relationship is difficult to understand, but it is possible
that women with complications expected difficult and
painful labour and, when labour progressed normally,
were relieved and perceived less pain