BACKGROUND The validity of studies on fecundability in Western countries has been questioned. The complexity of societal and cultural factors makes it difficult to dissect pure biological impact. Our aim was to assess couple fecundability in a population which to a large degree is unaffected by the same socio-cultural influences.

METHODS We conducted a prospective study on time-to-pregnancy (TTP), with a complete follow-up between 2005 and 2007, among 205 newly married couples in two Palestinian agricultural villages. The couples had never had premarital sex and all planned to become pregnant. We followed the couples from the date of marriage until pregnancy was recognized by a pregnancy test, or at maximum 12 months.

RESULTS Overall fecundability was 0.17. Unexpectedly, cycle fecundability increased during the first cycles from 0.16 (cycle 1) to 0.25 (cycle 5), after which the expected decline started. The initial increase in fecundability was restricted to couples with teenage brides. A total of 70.7% of the couples conceived within 6 cycles, 13.4% did not conceive during follow-up. Prolonged TTP was associated with the oldest age category for both genders. Educated women appeared to be highly fecund.

CONCLUSIONS The fecundability result is probably uninfluenced by the societal and cultural factors seen in Western populations, because premarital sex is a taboo in this Muslim population. The increase in fecundability during the first months following marriage is difficult to interpret, but could be due to either behavioural or biological influences.