Can hCG Levels Predict Multiple Pregnancy?
Pregnancy tests generally measure the hormone hCG, which is unique to pregnancy, in either the blood or urine. These tests are getting more and more sensitive and can turn positive as early as one week from conception. Although it is possible to quantify how much of this hormone is present and give a rough idea of how far along the pregnancy is, this would not be a usual use of this test.
If your test was positive sooner than you expected it to be, you may be off on your dates, but unless the exact amount of hCG is measured, it would not be indicative of a multiple gestation. If the lab did quantify the test, then twins would have more hCG than a singleton pregnancy. An ultrasound would answer the question best.
The best indications of gestational age are good dates -- knowing when you conceived -- if that is possible, and an early ultrasound. It would be very unlikely if you got pregnant on the pill, if taken correctly, unless you were on antibiotics or had vomiting or diarrhea, which would interfere with pill effectiveness.
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