More than six out of ten unplanned pregnancies in Britain occur in women aged 20-34 years, a national study has found. Age under 16 at first intercourse, smoking and low educational attainment were all associated with unplanned pregnancy.

This study was part of the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) which uses a stratified probability sample of 15,162 men and women aged 16-74 years in Britain.

Overall, 5,686 out of 8,869 women aged 16-44 years responded to this particular study, a response rate of 57.7%.

The distribution of pregnancies by planning status and the factors associated with unplanned pregnancy were measured using a validated psychometric measure – the London Measure of Unplanned Pregnancy (LMUP).

The LMUP overcomes the dichotomous assumptions about pregnancy intentions and allows interviewees to express some ambiguities with planning pregnancies; the higher the LMUP score, the greater the intention of the woman to get pregnant.

In this subset, 591 (10%) had a pregnancy with a known outcome in the year preceding the interview and completed the LMUP questionnaire. Forty four (7%) of the 591 women had more than one pregnancy in the past year. The proportion of pregnancies with a known outcome in the past year scored as unplanned according to the LMUP was 16.2%, ambivalent 29.0% and planned 54.8%.

Pregnancy planning status varied with age and pregnancy outcome. The mean LMUP score increased with age. Proportion of pregnancies scored as unplanned was highest among 16-19 year olds and lowest among those aged 25-29 years. The proportion of planned pregnancies was highest among women aged 30-34 years. Ambivalent pregnancies were most prevalent in women aged 16-24 years.

Pregnancies in women who were not cohabiting or those currently without a partner were more commonly unplanned than in those who were married or cohabiting.

Women with one child were more likely to have planned pregnancies compared with those without children or those with two or more children, before the most recent pregnancy.

Overall, the estimated proportion of women who had an unplanned pregnancy was 1.5%.

Unplanned pregnancies were strongly associated with sex before 16, lack of sexual competence, and receiving sex education from sources other than schools. They were also associated with having sex more than five times in the past four weeks, having more than one heterosexual partner in the past year, hard drug use, current smoking, current depression and lower educational attainment (no qualifications beyond minimum school leaving age).

This study highlights the need for effective contraception for women of all ages. The teenage pregnancy strategy has rightly concentrated on preventing unplanned pregnancies in under 19s where prevalence of unplanned pregnancies was highest (45.2%). This age group accounted for only 7.5% of the total number of pregnancies but 21.2% of the total of unplanned pregnancies.

More pregnancies occurred in women aged 20-34 years. This age group accounted for 62.4% (95% CI: 50.2-73.2) of all unplanned pregnancies. 

There is a substantial minority of women in all age groups who would have benefitted from reliable contraception, especially in the 20-24 age band which had an unplanned pregnancy rate of 17.4%. All other age groups had a prevalence > 10%.

Current QOF incentives for GPs only concentrate on providing advice on long acting reversible contraception (LARC) for women requesting emergency contraception. This and the now retired QOF marker to give LARC advice for women on hormonal contraception would completely miss women who are sexually active and not using any reliable method of contraception. Perhaps we need to return to the days of FP1001 – when all women were given advice on contraception.

Dr Richard Ma

• Wellings K, Jones KG, Mercer CH et al. The prevalence of unplanned pregnancy and associated factors in Britain: findings from the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3). Lancet 2013;382(9907):1807-16