Risk of Twin Pregnancy with Family History and Other Factors

Baseline Twin Rates and Risk Factors

The natural incidence of twin pregnancies follows a specific pattern, with a baseline rate of approximately 1 in 89 pregnancies, and twin pregnancy rates have been rising substantially due to assisted reproductive technologies, according to the American College of Radiology 1, 2
Dizygotic twins comprise approximately two-thirds of all twin pregnancies, as reported by the American College of Radiology 3, 4

Advanced maternal age is a factor that increases twin pregnancy risk, as noted by the American College of Radiology 3
Higher parity (number of previous pregnancies) also increases twin pregnancy risk, according to the American College of Radiology 4
Twin pregnancies carry significantly higher risks, including a 5-fold increase in fetal death and a 7-fold increase in neonatal death (primarily from prematurity), as reported by the American College of Radiology 1, 2, 3
Early diagnosis of twin pregnancy allows for appropriate risk stratification and monitoring, and is essential for women with a family history of twins, as recommended by the American College of Radiology 1, 2

The American College of Radiology recommends determining chorionicity as early as possible, preferably during the first trimester, when ultrasound accuracy approaches 100 %【5】.

The American College of Radiology advises that all twin pregnancies undergo nuchal‑translucency screening between 11 and 14 weeks gestation to assess for congenital anomalies【6】【5】.