Contraceptive Method at First Sexual Intercourse and Subsequent Pregnancy Risk: Findings from a Secondary Analysis of 16-Year-Old Girls from the RIPPLE and SHARE Studies
Received 6 December 2007; accepted 9 June 2008. published online 20 October 2008.
Abstract
Purpose
Existing failure rate studies indicate that typical use of oral contraception (OC) results in fewer unplanned pregnancies than condom use, even among teenagers. However, comparative data on pregnancy risk associated with different contraceptive methods are lacking for younger teenagers starting their first sexual relationship. This study examined associations between contraceptive method at first intercourse and subsequent pregnancy in 16-year-old girls.
Methods
Six thousand three hundred forty-eight female pupils from 51 secondary schools completed a questionnaire at mean age 16 years; 2,501 girls reported sexual intercourse. Logistic regression (N = 1952) was used to model the association of contraceptive method at first intercourse with pregnancy.
Results
At first intercourse (median age 15 years) 54% reported using condoms only, 11% dual OC and condoms, 4% OC only, 4% emergency contraception, and 21% no effective method. Method used was associated with a similar method at a most recent intercourse. One in 10 girls reported a pregnancy. When compared to use of condoms only, greater pregnancy risk was found with no effective method (odds ratio [OR] 2.97, 95% confidence interval [CI] 2.12–4.15) or OC only (OR 2.44, 95% CI 1.29–4.60). Pregnancy risk for dual use and emergency contraception did not differ from that for condoms only. Both significant effects were partially attenuated by adjusting for user characteristics and sexual activity.
Conclusions
Young teenagers may use OC less efficiently than condoms for pregnancy prevention. The characteristics of those using OC-only confirm vulnerability to unintended pregnancy, and suggest that alternative contraceptive strategies should be considered for these young women.
aMedical Research Council Social and Public Health Sciences Unit, University of Glasgow, Glasgow, United Kingdom
bUCL Centre for Sexual Health and HIV Research, Department of Primary Care and Population Sciences, University College London, London, United Kingdom
cSocial Science Research Unit, Institute of Education, University of London, London, United Kingdom
Address correspondence to: Alison Parkes, Ph.D., Medical Research Council Social and Public Health Sciences Unit, University of Glasgow, Glasgow, United Kingdom
The RIPPLE and SHARE (WBS U.1300.00.005) studies were funded by the UK Medical Research Council. The Health Education Board for Scotland funded the development of the SHARE program.
ABSTRACT