Effectiveness of a Postpartum Breastfeeding Protocol for Avoiding Pregnancy and Descriptive Analysis of the Physiology of the Postpartum Transition

Traditionally, postpartum breastfeeding women used Natural Family Planning (NFP) methods that required observation of cervical mucus and basal body temperature as indicators of return to fertility. These indicators resulted in high unintended pregnancy rates (i.e., 14-32 over 12 months of use). High pregnancy rates were due to the inaccuracy and subjectivity of those fertility indicators which required extended periods of abstinence. Ineffectiveness of NFP methods is also related to changing patterns of fertility during lactation amenorrhea (LA) and the first six menstrual cycles postpartum.Studies of a NFP protocol where women used objective urine hormone biomarkers were 92-98% effective for avoiding unintended pregnancy while in LA. The protocol has women test urine pre-ovulatory estrogen (E3G) and luteinizing hormone with an electronic home fertility monitor. In 2013 a revised protocol was published. The revised protocol increased daily testing to twice a day and added instructions for the initial menstrual cycles. The purposes of this study were to describe the physiological breastfeeding transition to fertility from LA through the first six cycles postpartum and to evaluate the correct and typical use effectiveness pregnancy rates of the revised protocol at 12 months and 12 cycles of use. This repeated measures quasi-experimental (n = 216) and descriptive study (n= 64) used an established data set from an archived NFP website. Kaplan-Meier survival rate analysis showed four unintended pregnancies per 100 women at 12 months and 6 per 100 women at 12 cycles of use. A descriptive analysis of LA\u27s length and the following 6 cycles found LA and cycle one positively skewed. Cycles two through six were normally distributed. On average, 89% of the women experienced an estimated day of ovulation (EDO). The EDO occurred around 8 months and first menses around 9 months. In cycle one, the EDO occurred around day 28, and in cycles two through six, the EDO occurred between days 19-22. Comparison between the original and revised protocols found menstrual cycle parameters and characteristics of the first menses were near identical. Findings from this study were used to develop new algorithms to improve accessibility of the protocol