Scientific bases for NFP beyond question

The Couple to Couple League (CCL) is pleased that an article and an editorial in the December 1995 issue of the well-respected New England Journal of Medicine confirm that natural family planning (NFP) has value and is scientifically based, a fact the CCL has known for many years. The research covered in the article entitled Timing of Sexual Intercourse in Relation to Ovulation found that the only fertile days were the five days before ovulation and the day of ovulation itself. Most conceptions (76.4%) occurred during the day of and the first and second days before ovulation. CCL's slide showing the extent of the fertile time reflects the data of the report, but also includes the possibility of a second ovulation occurring within 24 hours of the first ovulation. The study found that women conceived in only 37% of cycles in which intercourse took place during the six-day fertile period. This rate is not much different than that claimed by a NFP physician many years ago (about 30%). The study showed the highest conception probability to be when the couple had sexual intercourse every day during the fertile period (37% vs. 33% for every other day). CCL advises couples to abstain until the fertile period then follow one coital frequency period during one cycle (e.g., every day) and the other pattern the next cycle (e.g., every other day). The study refuted claims that the timing of coitus relative to ovulation was not associated to the sex of the baby and that aging sperm do not reduce the viability of the fetus and/or cause birth defects. In fact, aging sperm rarely fertilize the ovum. The only way to positively detect ovulation is seeing the ovum burst out of the ovary. Hormone analyses of blood or urine and observations of cervical mucus and basal body temperature allow an estimate of the day of ovulation. NFP is not based on detecting ovulation but on identifying the limits of the fertile period.