Why is the gestational age of a pregnancy often calculated based on the last menstrual period (LMP) rather than conception, and how do HCG levels correlate with this method of dating?
Gaurav ChauhanContributor
What if my HCG levels were 179 on Monday and Wednesday and they just went to 185?
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The gestational age is based on LMP because the exact conception date is often unknown. hCG levels rise predictably after conception, helping to estimate gestational age.
The gestational age is calculated from the last menstrual period (LMP) because the exact moment of conception is often unknown. HCG levels, which rise rapidly after conception, help confirm the pregnancy timeline established by the LMP date.