‘Chemical Pregnancies’ Are Often Mistaken for Miscarriages

An estimated 20% to 25% of all pregnancies will be “lost” shortly after conception, but the problem poses no continuing obstacle for most women who want to have children.

This type of loss is called a “chemical pregnancy.”

Today’s sensitive home pregnancy tests can let a woman know if she has conceived within a day or two of a missed menstrual period.

Often a patient will get a positive result, then begin to bleed a few days or a week later at or around the time of the expected period. She may mistakenly believe she’s had a miscarriage.

Although there was a loss because conception did take place, this is not a bad prognostic sign. It proves a woman’s Fallopian tubes are open, that her ovaries produce eggs, that her husband makes sperm and that her cervical mucus is capable of carrying the sperm to the egg.

In fact, 35% of women who experience such early losses will become clinically pregnant the next month--have a pregnancy that is detectable on ultrasound. And 65% of these women will become pregnant within three months, and most will successfully carry to term.

It is believed that many early losses are due to chromosomal abnormalities, maternal illness or harmful exposures.

In some cases, the loss may be due to inadequate amounts of the female hormone progesterone in the second half of a woman’s menstrual cycle.

More than 70% of losses in the embryonic stage, or between five and 10 weeks from a woman’s last menstrual period, may be simply nature’s way of dealing with severe chromosomal abnormalities or major developmental defects.

Miscarriages in the fetal period of pregnancy, between 10 and 26 weeks, are often a different matter. They may be because of physical problems, such as a defect in the uterus or cervix that interferes with pregnancy, or a serious maternal illness.

If there’s a defect in the cervix or scar tissue in the uterus from previous surgery, the problem can often be corrected and a future miscarriage prevented.

If a woman is at risk of miscarrying, doctors can perform an immediate ultrasound examination to give her more information.

It is most important for a woman to understand that losing a pregnancy is almost never due to anything that she did. The pregnancy usually has lost its viability one to four weeks before the onset of bleeding. So women should be reassured that if they went dancing, skiing or played tennis and then promptly miscarried, this was not the cause of their loss.

And in most cases, a woman can successfully conceive again, carry to term and have a healthy baby.

Steven Goldstein is an obstetrician-gynecologist at New York University Medical Center.