The genotype of the mother and the fetus influences the efficacy of a teratogen. For example, genotype determines the prevalence of cleft palate in inbred strains of mice whose mothers are administered cortisol during pregnancy.
Most women will not start ovulating in the first six weeks after giving birth.1 Breastfeeding typically delays the onset of ovulation.2 Depending on the intensity of breastfeeding, it can be several months or over a year before you regain your fertility.
Nonbreastfeeding women ovulate for the first time, on average, 45 days after giving birth. A new mom who chooses not to breastfeed will usually ovulate between the 25th and 72nd days after giving birth. Forty-five days is the average.