Terms Explained: what is a heterotopic pregnancy?

You may have heard of an ectopic pregnancy (when an embryo implants outside the uterus; sadly, in such a situation the embryo cannot survive). And now, with more scientific resources being devoted to pregnancy, you may begin to hear the term “heterotopic pregnancy” as well.

A heterotopic pregnancy is when twins are conceived and one implants in the uterus and one implants outside the uterus.

Heterotopic pregnancy is very rare in natural conception (chance is 1/30,000), but the incidence is on the rise with the commonization of assisted reproductive technologies. This means that doctors are more aware that heterotopic pregnancy is a possibility and may check for a uterine pregnancy if they establish that there is an ectopic pregnancy. Usually, a heterotopic pregnancy is identified between 5 and 8 weeks gestation. Often, a pregnant person comes to the ER with abdominal pain because of the ectopic pregnancy. ER doctors will often perform an ultrasound, and it is through that imaging that they can diagnose a heterotopic pregnancy.

An embryo that has implanted outside of the uterus cannot survive, so ectopic pregnancy is always fatal for the extrauterine embryo. That loss can be heartbreaking. The resulting wave of emotions can be even more complicated when someone learns that there are two pregnancies – one extrauterine and one intrauterine. In addition to grief over the loss of one child, one might experience fear regarding the health of the other child. The intrauterine embryo has a much better range of prognoses that their twin. After their twin has passed away, the intrauterine embryo’s only risk factor associated with miscarriage is gestational age (which is a key risk factor associated with miscarriage generally).

If you think you are experiencing an ectopic or heterotopic pregnancy, contact a medical professional immediately. If you are looking for support or for ideas of how to support a loved one, reach out to me through the contact form above.

References: 
Goettler, Simone, and Rosanna Zanetti-Dällenbach. 2016. “Heterotopic Pregnancy.” New England Journal of Medicine.
Na, Eun Duc, Inkyung Jung, Dong Hee Choi, Hwang Kwon, Seok Jae Heo, Hyeon Chul Kim, Suk Ho Kang, and HeeYoung Cho. 2018. “The Risk Factors of Miscarriage and Obstetrical Outcomes of Intrauterine Normal Pregnancy Following Heterotopic Pregnancy Management.” Medicine 97(37).