Complex sentence: During sexual intercourse, the interaction between the male and female reproductive systems results in fertilization of the woman's ovum by the man's sperm, which after a gestation period, typically for nine months, is followed by childbirth.
Split into simpler sentences: During sexual intercourse, the interaction between the male and female reproductive systems results in fertilization of the woman's ovum by the man's sperm. After a gestation period, typically for nine months, is followed by childbirth.