THE FREQUENCY AND SPECTRUM OF CONGENITAL-ANOMALIES IN NATURAL FAMILY-PLANNING USERS IN SOUTH-AMERICA - NO INCREASE IN A CASE-CONTROL STUDY

Users of natural family planning (NFP) practice periodic abstinence, l eading many to reason that such couples should show increased anomalie s in offspring as a result of fertilization involving aging gametes. I n an effort to complement our NFP cohort study, we currently conducted a case-control study in the same region (South America) in which the largest number of cases have been recruited for our cohort NFP study. During 1992-94, 5324 case-control pairs of mothers were interviewed du ring the immediate postpartum period in 18 maternity hospitals partici pating in the Latin-American Collaborative Study of Congenital Malform ations: ECLAMC (Spanish acronym for Latin-American Collaborative Study of Congenital Malformations). Natural family planning (NFP) usage was recorded in 6% of mothers in the ECLAMC sample studied (n = 10 648). Overall, no significant differences in frequency of NFP usage were obs erved between malformed cases (349/5324 = 6.6%) and normal controls (3 03/5324 = 5.7%) (chi(2) = 3.3; df = 1; p > 0.05). No significant diffe rences in sex ratios were observed between children of NFP user and no n-user mothers. Of special interest is the lack of association between NFP and Down syndrome, the sentinel phenotype for the hypothesis of d elayed fertilization (aging gametes).