A survey of contraceptive use and unplanned pregnancy in Perth, Western Australia

Abstract

Contraceptive use and unplanned pregnancy were studied in a stratified cluster sample of 1,511 couples with women aged 16 to 44 years resident in metropolitan Perth in 1988. Twenty-one couples were excluded from analysis owing to missing data. The proportion of couples using contraception was 76.8 per cent (1,144 of 1,490), and all but three of the remaining couples gave a reason for nonuse. Among users, surgical sterilisation made up 42.3 per cent (484 of 1,144) of all methods, with a slight predominance of tubal ligation over vasectomy. Oral contraceptives accounted for just over half of nonsurgical methods. Comparisons with a Victorian survey performed in 1978 suggested that surgical methods and condom use may have increased, whereas use of oral contraceptives and intrauterine devices may have fallen. Unplanned pregnancies conceived during the 12 months before the interview affected 3.4 per cent (51 of 1,490) of respondents. The incidence of unplanned pregnancy was four times higher in couples with inconsistent usage patterns of contraception.

PIP: In September-December 1988 in Australia, at least 1490 couples in metropolitan Perth completed a questionnaire on contraceptive use and unplanned pregnancy. 76.8% of all couples used contraception. Surgical sterilization was the leading contraceptive method (42.3% of users [23% tubal ligation and 19.3% vasectomy]), followed by oral contraceptives (OCs) (33.2%) and condoms (10%). Combined OCs were the major OCs (74.7%), followed by the mini-pill (i.e., progestogen only OC) (16.6%). 77.1% of contraceptive-using couples used contraception during every sexual episode. Only 0.8% used contraception inconsistently. Only 0.2% of nonusers gave no apparent reason for not using contraception. Common reasons for not using contraception were, in order of frequency: trying to conceive, pregnancy within the last year, hysterectomy, infertility, and recent newborn. 51 (28%) of the 182 women who had become pregnant within the last 12 months did not plan the pregnancy, equalling an unconditional cumulative incidence of unplanned pregnancy of 3.4% (51 of 1490 women). The cumulative incidence of unplanned pregnancy among the 714 at-risk couples was 7.1% (i.e., excluding infertile and sterilized couples, those with a planned pregnancy and those wanting to conceive). The unplanned pregnancy rate among couples not using contraception was 25%. The unplanned pregnancy rate among consistent users was only 3.6% compared to 14.8% for inconsistent users and 16.7% for seldom users (p .0001). Surgical sterilization and condom use was higher in 1988 in Perth than it was in 1978 in Victoria (42.3% and 10% vs. 25% and 4%, respectively). On the other hand, OC use and IUD use fell between 1978 and 1988 (47% vs. 33.2% and 11% vs. 5.9%, respectively).