Chemical Pregnancy

30% of pregnancies are believed to be lost very early in pregnancy, even before implantation. Another 30% have been reported to be lost soon after implantation and before a missed period.

What happens in a chemical pregnancy?

In both, a normal pregnancy and a chemical pregnancy, within a week after fertilization, the resulting embryo implants into the uterine wall. Soon after implantation, the pregnancy hormone, hCG is produced, which is detected in a positive pregnancy test. However, while in a normal pregnancy, implantation is followed by the growth and development of the embryo, in a chemical pregnancy, the embryo dissolves from the uterus and becomes non-viable within five weeks of implantation.

What are the symptoms of chemical pregnancy?

Most chemical pregnancies happen even before the pregnant mother would come to know about the conception. Most often, a positive result on the pregnancy test followed by a negative result in a few weeks or days is how a chemical pregnancy is identified.

As chemical pregnancy wouldn’t last until the first ultrasound scan, which is usually around 6 or 7 weeks, it wouldn’t show up on the scan. Hence, a positive result in the pregnancy test (at 4 or 5 weeks) along with the absence of a gestational sac in an ultrasound scan, followed by a period is a sign of chemical pregnancy. However, in this case, the chances for a false positive result on the pregnancy test cannot be ruled out.

Some women may have symptoms of chemical pregnancy like abdominal cramping, implantation bleeding and a missing period which are also signs of a normal pregnancy. However, in spite of these symptoms, if an embryo or gestational sac cannot be located in an ultrasound, it could be because of chemical pregnancy.

If you suspect a chemical pregnancy, contact your healthcare provider. He/she must be able to access the situation based on clinical evidence.

Is chemical pregnancy different from miscarriage?

Chemical pregnancy is considered as an early miscarriage which happens within six weeks of gestation, even before anything can be detected in an ultrasound. In medical terms, it is called as a biochemical loss while a miscarriage, in general, refers to death of the fetus after the confirmation of the presence of an embryo or gestational sac through an ultrasound scan and up till 21 weeks of gestation. 50-75% of miscarriages have been found to be of chemical pregnancy.

What are the causes of chemical pregnancy?

What causes chemical pregnancy is not clearly understood yet. Studies link chemical pregnancy to the following:

·         Chromosomal abnormalities of the parents

·         Thyroid disorders

·         Hormonal imbalance

·         Infections such as Chlamydia or Syphilis

·         Mother’s immune response to the fetus

·         Ovarian cysts

·         Uterine wall problems

·         Thrombophilia (abnormal blood clotting)

·         Alcohol consumption

·         Smoking-related complications

·         Obesity or under-weight

How does chemical pregnancy impact future pregnancies?

In general, chemical pregnancy does not affect fertility or child-bearing ability in subsequent pregnancies. A woman who had a chemical pregnancy can conceive in her immediate next cycle, that is, as early as two weeks after a chemical pregnancy, unless advised by a doctor not to.

What is helpful to understand before re-attempting conception, however, is the reason for a previous chemical pregnancy. Chemical pregnancies because of an infection or a thyroid disorder carry the risk of repetition in future pregnancies. For instance, treating an infection with antibiotics or getting treated for a hormonal imbalance is more likely to decrease the risk of another chemical pregnancy. Hence, tt is best to consult a doctor in order to access underlying reasons if any, of a chemical pregnancy, to prevent a re-occurrence.

Chemical pregnancy in women undergoing IVF is a sign for good as it assures the possibility of fertilization and implantation, though it can cause temporary grief. In most IVF cases, chemical pregnancy is followed by a subsequent successful pregnancy.

Reference

Larsen, E. C., Christiansen, O. B., Kolte, A. M., & Macklon, N. (2013). New insights into mechanisms behind miscarriage. BMC medicine, 11, 154. doi:10.1186/1741-7015-11-154  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3699442/#B18