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 hard to pinpoint when you can expect your menstrual cycle to return after giving birth. However, the average for women who are not breastfeeding is between six and eight weeks postpartum. Approximately 80% of non-nursing mothers will have their period by the time they are 10 weeks postpartum.ou are more likely to have no periods while breastfeeding if you're exclusively nursing and your baby does not use a pacifier. In most cases, the rule of thumb is that it's perfectly normal to wait up until six months after you're finished breastfeeding for your menstrual cycle to return.