Pregnancy outcome in natural family planning users: cohort and case-control studies evaluating safety
- 17 Downloads
Conceptions involving aging gametes are of relevance to natural family planning (NFP) because women using NFP to avoid pregnancy abstain from intercourse during the fertile time of the cycle. To help verify the safety of pregnancies occurring among NFP practitioners, our group has, since 1986, conducted a large cohort study involving six experienced NFP centers. Timing of conception was determined from NFP charts, in which women recorded days on which intercourse occurred. The number of days from the most probable conception intercourse to probable day of ovulation was first determined, and used as an estimate of the time gametes remained in the genital tract before fertilization. Several studies have already been completed, cohort as well as case-control in nature.
1. Spontaneous abortions. Three hundred and sixty-one conceptions occurred during the optimal time (day -1 or 0 relative to ovulation), and of these 33 resulted in spontaneous abortion (9.1%). Five hundred and seven conceptions occurred at non-optimal times during the cycle, and of these 55 resulted in spontaneous abortions (10.9%). These differences were not statistically significant (relative risk 1.19, 95% CI, 0.79-1.80) .
2. Anomalies. Among 780 singleton births in 868 cohort pregnancies, 24 infants had major anomalies (3.1%) as of the present analysis . This frequency is comparable to the general population. To further assess anomalies we employed a case-control approach. All consecutive births (live and stillborn) weighing 500 g or more taking place in 18 participating South American hospitals were examined for minor and major congential anomalies. Mothers of malformed and control infants did not differ with respect to the reported frequency of NFP use, which overall was 6.3% of the 10 642 mothers interviewed (5277 having a malformed infant; 5371 controls). Of 262 discordant pairs, there were 28 or 10.69% mothers within the Down syndrome case group vs. 16/262 or 6.11% among matched controls [3,4]. The odds ratio was 1.84; 95% CI, 0.99-3.96; however, even this non-significant difference narrowed substantially when adjusted for maternal age (OR, 1.78; 95% CI, 0.84-3.75); parity (OR, 1.68; 95% CI, 0.87-3.24); maternal educational level (OR, 1.71; 95% CI, 0.86-3.44); or all three together (OR, 1.74; 95% CI, 0.83-3.64).
Conclusions. Our findings should be reassuring to natural family planning users. The overall rate of spontaneous abortion was not increased in NFP users who became pregnant, nor to date was the rate of anomalies. Any contribution to Down syndrome or abortion due to aging gametes would have to be small.
Unable to display preview. Download preview PDF.
- 1.Gray RH, Simpson JL, Kambic RT et al. Timing of conception and the risk of spontaneous abortion among pregnancies during use of natural family planning. Am J Obstet Gynecol. 1995; 172: 1567–72.Google Scholar
- 2.Simpson JL, Gray RH, Queenan JT et al. Is the frequency of anomalies increased in o¡spring conceived by `aged' gametes? VI World Congress, International Federation of Family Life Professionals (IFFLP/ FIDAF), Lublin, Poland, September, 1994. Abstract no.V-2.Google Scholar
- 3.Castilla EE, Simpson JL, Queenan JT. Down syndrome is not increased in o¡spring of natural family planning users (case control analysis). Am J Med Genet. 1995; 59: 525.Google Scholar
- 4.Castilla EE, Simpson JL, Queenan JT. Clari¢cation of ECLAMC/NFP case control study. Am J Med Genet. 1996; 66: 364.Google Scholar
- 5.Simpson JL, Gray RH, Queenan JT et al. Pregnancy outcome associated with natural family planning (NFP): Scienti¢c basis and experimental design for an international cohort study. Adv Contracept. 1988; 4: 247–64.Google Scholar
- 6.Simpson JL, Gray RH, Queenan JT et al. Fetal outcome among pregnancies in natural family planning acceptors: an international cohort study. Am J Obstet Gynecol. 1991; 65: 1981–2.Google Scholar
- 7.Castilla EE, Simpson JL, Queenan JT. Down syndrome in natural family planning. Am J Med Genet. 1996; 66: 366.Google Scholar
- 8.Tesh JM, Glover TD. Aging of the rabbit spermatozoa in the male tract and its e¡ect on fertility. J Reprod Fertil. 1969; 20: 287–97.Google Scholar
- 9.Martin-DeLeon PA, Boice ML. Sperm aging in the male after sexual rest: contribution to chromosome anomalies. Gamete Res. 1985; 12: 151–63.Google Scholar
- 10.Martin-DeLeon PA, Shaver EL. Sperm aging in utero and chromosomal anomalies in rabbit blastocytes. Dev Biol. 1972; 28: 480–6.Google Scholar
- 11.Witschi E. Overripeness of the egg as a cause of twinning and teratogenesis: A review. Cancer Res. 1952; 12: 763–86.Google Scholar
- 12.Witschi E, Laguens R. Chromosomal aberrations in embryos from overripe eggs. Dev Biol. 1963; 7: 605–16.Google Scholar
- 13.Vickers AD. Delayed fertilization and chromosomal anomalies in mouse embryos. J Reprod Fertil. 1969; 20: 69–76.Google Scholar
- 14.Shaver EL, Carr DH. The chromosome complement of rabbit blastocysts in relation to the time of mating and ovulation. Can J Genet Cytol. 1969; 11: 287–93.Google Scholar
- 15.German J. Mongolism, delayed fertilization and human sexual behavior. Nature (London). 1968; 21: 516–8.Google Scholar
- 16.Kinsey AC, Pomeroy WB, Martin CE, Gebhard PH. Sexual behavior in the human female. New York: Saunders; 1953.Google Scholar
- 17.Juberg RC, Goshen CR, Sholte FG. Socioeconomic and reproductive characteristics of the parents of patients with GI trisomy syndrome. Soc Biol. 1973; 20: 404–15.Google Scholar
- 18.Milstein-Moscati IM, BecakW. Down syndrome and frequency of intercourse. Lancet. 1978; 2: 629–30.Google Scholar
- 19.Juberg RC. Origin of chromosome abnormalities: Evidence for delayed fertilization in meiotic nondisjunction. Hum Genet. 1983; 64: 122–7.Google Scholar
- 20.Jongbloet P, Paesrkote A. Down's syndrome and religious groups. Lancet. 1978; 2: 1310.Google Scholar
- 21.Mulcachy M. Down's syndrome and parental coital rate. Lancet. 1978; 2: 895.Google Scholar
- 22.Sharav T. Aging gametes in relation to incidence, gender and twinning in Down syndrome. Am J Med Genet. 1991; 39: 116–18.Google Scholar
- 23.Boue J, Boue A, Lazar P. Retrospective and prospective epidemiological studies of 1500 karyotyped spontaneous human abortions. Teratology. 1975; 12: 11–26.Google Scholar
- 24.World Health Organization. A prospective multicenter study of the ovulation method of natural family planning IV. The outcome of pregnancy. Fertil Steril. 1984; 41: 593–8.Google Scholar
- 25.France JT, Graham FM, Gosling L, Hail PI. A prospective study of preselection of the sex of o¡spring by timing intercourse relative to ovulation. Fertil Steril. 1984; 41: 894–900.Google Scholar
- 26.Roetzer J. Natural family planning and pregnancy outcome. Int J Fertil. 1988; 33(suppl.)40–2.Google Scholar
- 27.Marshall J. Congenital defects and the age of spermatozoa. Int J Fertil. 1968; 134: 110–20.Google Scholar
- 28.GuerreroV, Rojas OI. Spontaneous abortion and aging of human ova and spermatozoa. N Engl JMed. 1975; 293: 573–5.Google Scholar
- 29.Kambic R, Gray RH. Interobserver variation in estimation of conception intercourse using selected natural family planning charts. Fertil Steril. 1989; 51: 430–4.Google Scholar
- 30.Castilla EE, Mutchinick OM, Paz JE, Munoz EN, Gelman Z. Estudio latinoamericane sobre malformaciones congenitas. Bol O¢ Sanit Panam. 1974; 76: 494–502.Google Scholar