PURPOSE: Given reportedly high clustering but limited validity of retrospectively reported @entity1054 ( @entity1054 ), we assessed within- @entity1 clustering for retrospectively reported TTPs alone and including gold-standard prospectively observed TTPs among @entity1 with 2 or more retrospectively reported and 1 or more prospectively observed TTPs. We further investigated whether past trying times inform future trying time among @entity1 with 1 or more retrospectively reported and 1 or more prospectively observed TTPs. METHODS: Five hundred one couples attempting pregnancy were prospectively observed until @entity1 chorionic gonadotropin pregnancy or 12 months of trying. @entity1 reported @entity1054 for past planned pregnancies. Clustering as measured by the frailty variance was estimated using discrete Cox frailty models, adjusted for age, body mass index, smoking at each attempt. Utility of past attempts to inform future attempts was assessed with discrete Cox models and relative risk regression, adjusted for enrollment age, body mass index, smoking. RESULTS: Seventy-five @entity1 with 2 or more prior pregnancies contributed 180 retrospective and 91 prospective TTPs for frailty modeling. Retrospectively reported @entity1054 clustering was high (frailty variance = 0.89) but substantially lower when including prospectively observed TTPs (frailty variance = 0.42). Among 202 @entity1 with 1 or more prior pregnancies, past trying times did not inform future trying time. CONCLUSIONS: @entity1054 recall rather than @entity1054 may account for clustering. Past trying times may not inform future trying times.

Clustering of retrospectively reported and prospectively observed XXXX .

@entity1 :: ('9606', 'Species') :: ['women', 'woman', 'human', 'Women'] @entity1054 :: ('MESH:D000377', 'Disease') :: ['TTP', 'time-to-pregnancy']
@entity1054 :: (MESH:D000377,Disease) :: ['time-to-pregnancy']
