Stillbirths occurs when a fetus dies after 20 weeks of gestation. It is within the uterus that the fetus develops during gestation. The normal period of gestation (pregnancy) is about nine months or 40 weeks. A fetus born prior to the 37th week of gestation is considered to be "preterm". The placenta is considered an ephemeral organ present during gestation and pregnancy. PROM is responsible for 20% of all fetal deaths between 24 and 34 weeks' gestation. The fetus's sex can be determined by day 70 of the gestation using ultrasound. The female gives birth to one offspring per gestation. A pregnancy is considered "term" at 37 weeks of gestation. This is particularly true if the pregnancy is beyond 34 weeks of gestation. She gave birth at just shy of 30 weeks gestation. She was refused due to the foetus being of a viable gestation. In mammals with longer gestation periods, muscle spindles are fully formed at birth. Having a large placenta (multiple gestation, hydatidiform mole) also predisposes women to eclampsia. Calves are born after a gestation of nine months.