Question 1

How is a pregnancy due date calculated?

Accepted Answer

Naegele's Rule is the standard method: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a 28-day cycle. If your cycle is longer or shorter, the ovulation date shifts accordingly. Ultrasound dating in the first trimester is the most accurate method.

Question 2

What is a full-term pregnancy?

Accepted Answer

A full-term pregnancy is 39-40 weeks. Early term is 37-38 weeks, late term is 41 weeks, and post-term is 42+ weeks. Babies born before 37 weeks are considered premature. The American College of Obstetricians and Gynecologists recommends waiting until at least 39 weeks for elective deliveries.

Question 3

How accurate is an estimated due date?

Accepted Answer

Only about 5% of babies are born on their exact due date. About 80% are born within 2 weeks of the EDD. First-time mothers tend to deliver slightly later than their due date. Ultrasound dating before 14 weeks is accurate to within 5-7 days; later ultrasounds are less precise.

Question 4

What is the difference between gestational age and fetal age?

Accepted Answer

Gestational age is counted from the first day of the last menstrual period (LMP) and is the standard medical measurement. Fetal age (conceptional age) is counted from conception, which is typically 2 weeks after LMP. When doctors say you are 10 weeks pregnant, they mean 10 weeks gestational age, which is about 8 weeks since conception.

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