Prevalence of<unk>  may vary between countries due to different population characteristics or medical management. Factors include number of first-time pregnancies, genetic predisposition, timing of ultrasound assessment, and Caesarean section rates, etc. The incidence is approximately 7%.<unk>  occurs in 0.4% of pregnancies approximately in the United States according to birth certificate data.
Postterm pregnancy
Male pregnancy
Teenage pregnancy
Pre-existing disease in pregnancy
Unintended pregnancy
Pregnancy loss
High-risk pregnancy
Pregnancy