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.
It is possible to have one or (occasionally) more periods before you start ovulating. In this case, menstruation begins during the first stage of the return to fertility âbefore ovulation returns. Cycles without ovulation are most common during the first six months postpartum. For other mothers, the first menstruation is preceded by ovulation â a longer period of lactational amenorrhea increases the likelihood that you will ovulate before that first period.