TY - JOUR

T1 - Feasibility of the current-duration approach to studying human fecundity.

AU - Slama, Rémy

AU - Ducot, Béatrice

AU - Carstensen, Lisbeth

AU - Lorente, Christine

AU - de La Rochebrochard, Elise

AU - Leridon, Henri

AU - Keiding, Niels

AU - Bouyer, Jean

N1 - Keywords: Adolescent; Adult; Age Factors; Bias (Epidemiology); Cohort Studies; Coitus; Cross-Sectional Studies; Family Planning Services; Female; Fertility; Humans; Male; Patient Selection; Pregnancy; Probability; Questionnaires; Smoking

PY - 2006

Y1 - 2006

N2 - Approaches for monitoring time trends in couples' fecundity and for studying its sensitivity to environmental factors are needed. Two approaches rely on the inclusion of a cross-sectional sample of couples currently "at risk" of pregnancy either with follow up (prevalent cohort) or without follow up (current-duration design). To illustrate the feasibility of the current-duration design, we contacted a random sample of 1204 French women age 18 to 44 years in 2004 and recruited those who were currently having unprotected sexual intercourse. The current duration since the beginning of unprotected intercourse was defined for 69 women (5.7%). An additional 15 women (1.2%) were planning to start trying to become pregnant within the next 6 months. Parametric methods allowed, based on current duration of unprotected intercourse, estimation of fecundity as if the couples had been followed prospectively. The estimated proportion of couples not pregnant after 12 months of unprotected intercourse was 34% (95% confidence interval [CI] = 15-54%). The accelerated-failure time model allows study of the influence of environmental factors on fecundity. As an illustration, tobacco smoking by the woman was associated with a doubling in the median duration of unprotected intercourse before pregnancy (adjusted time ratio = 2.4; 95% CI = 1.1-5.2). We quantified the influence of time trends in the prevalence of smoking on this estimate. We suggest ways to quantify or avoid other potential bias. In conclusion, it is possible to recruit a sample of couples currently having unprotected intercourse. The current-duration design appears feasible with approximately 5 times as many women eligible for study as for an incident cohort design. Udgivelsesdato: 2006-Jul

AB - Approaches for monitoring time trends in couples' fecundity and for studying its sensitivity to environmental factors are needed. Two approaches rely on the inclusion of a cross-sectional sample of couples currently "at risk" of pregnancy either with follow up (prevalent cohort) or without follow up (current-duration design). To illustrate the feasibility of the current-duration design, we contacted a random sample of 1204 French women age 18 to 44 years in 2004 and recruited those who were currently having unprotected sexual intercourse. The current duration since the beginning of unprotected intercourse was defined for 69 women (5.7%). An additional 15 women (1.2%) were planning to start trying to become pregnant within the next 6 months. Parametric methods allowed, based on current duration of unprotected intercourse, estimation of fecundity as if the couples had been followed prospectively. The estimated proportion of couples not pregnant after 12 months of unprotected intercourse was 34% (95% confidence interval [CI] = 15-54%). The accelerated-failure time model allows study of the influence of environmental factors on fecundity. As an illustration, tobacco smoking by the woman was associated with a doubling in the median duration of unprotected intercourse before pregnancy (adjusted time ratio = 2.4; 95% CI = 1.1-5.2). We quantified the influence of time trends in the prevalence of smoking on this estimate. We suggest ways to quantify or avoid other potential bias. In conclusion, it is possible to recruit a sample of couples currently having unprotected intercourse. The current-duration design appears feasible with approximately 5 times as many women eligible for study as for an incident cohort design. Udgivelsesdato: 2006-Jul

U2 - 10.1097/01.ede.0000221781.15114.88

DO - 10.1097/01.ede.0000221781.15114.88

M3 - Journal article

C2 - 16755258

VL - 17

SP - 440

EP - 449

JO - Epidemiology

JF - Epidemiology

SN - 1044-3983

IS - 4

ER -