noun
gestational age (in weeks)
Medical term used in obstetrics to describe the duration of pregnancy in weeks from the first day of the last menstrual period.
在胎週数が37週未満の出産は早産とみなされる。
Delivery before 37 weeks of gestational age is considered preterm.
超音波検査で在胎週数を推定する。
Gestational age is estimated by ultrasound examination.
妊娠週数 is a more general term for weeks of pregnancy, while 在胎週数 specifically refers to the gestational age of the fetus, often used in clinical contexts.
Compound of 在胎 (zaitai, 'in utero') + 週数 (shūsū, 'number of weeks'). The term is a modern medical coinage.