Gestational age

Gestational age is a measure of the age of a pregnancy which is taken from the woman's last menstrual period (LMP), or the corresponding age of the gestation as estimated by a more accurate method if available. Such methods include adding 14 days to a known duration since fertilization (as is possible in in vitro fertilization), or by obstetric ultrasonography. The popularity of using such a definition of gestational age is that menstrual periods are essentially always noticed, while there is usually a lack of a convenient way to discern when fertilization occurred.

The initiation of pregnancy for the calculation of gestational age can be different than the definitions of start of pregnancy in context of the abortion debate or beginning of human personhood.

Calculation

Gestational age can be kind of confusing, since it measures pregnancy from your last period — about 3-4 weeks BEFORE you’re actually pregnant. Common confusion happens when people try to count weeks of pregnancy starting with the day of conception — which could be 5-6 weeks AFTER your period, and 1-2 weeks AFTER you’ve missed your period.

A normal pregnancy can last anywhere between 38 and 42 weeks. Even though 40 weeks is still considered full term, you’re actually a little bit pregnant by the time you miss your period.

Methods of estimating gestational age

Several methods exist for the estimation of gestational age, including:

• Menstrual history
• Clinical examination
• Doppler ultrasonography
• Human chorionic gonadotropin (hCG) level

See also

• Pregnancy
• Obstetric ultrasonography
• Human chorionic gonadotropin
• In vitro fertilization

References

Gestational age Resources
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