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.
A: It is possible to have vaginal bleeding without ovulation. Your regular menstrual periods come every 21-35 days and last on average 3-6 days. You can have vaginal bleeding even if you don't ovulate. It's just not as regular as menstrual periods that follow ovulation.