Pregnancy Reduction in a Twin Pregnancy

A 35-year-old with several children discovers she is having a twin pregnancy. This is happy news, until a potential abnormality in twin B is found. 

Twin B is measuring much smaller than twin A — almost a full 10 to 14 days behind — and there is fluid around the fetus. While it is too early to diagnose, it appears there is a brain abnormality.

The patient, with a lot of apprehension and many questions, sees high-risk obstetrician Dr. Maeve Hopkins. Genetic testing is needed for decision-making — to help determine if twin B can survive or if the patient’s life and twin A are at risk, meaning a pregnancy reduction will need to be considered. Dr. Hopkins orders a biopsy of twin B’s placenta.

The results from genetic testing reveal that twin B has three sets of chromosomes, instead of two. This results in a rare genetic condition that causes severe birth defects. Most pregnancies in this situation end in either miscarriage or stillbirth. While there are very rare cases of live births, survival is generally limited to an average of five to seven days.

Carrying the fetus poses significant risk to both the patient and twin A. There could be a build up of amniotic fluid and difficulty swallowing for twin B, which could lead to preterm labor symptoms and birth, as well as stillbirth. Losing twin B in utero may increase the risk of losing twin A and put the patient at risk, too.

In this case, there are two options.

One is expectant management, which is essentially to wait and see. The other is a multi-fetal pregnancy reduction, where the cardiac activity of twin B is stopped, and the patient continues with a single twin pregnancy. While pregnancy reduction is considered a fairly safe procedure, there is a small risk that the patient could still lose twin A.

“I think she was somewhat in shock,” Dr. Hopkins shared. “And I think she wanted some guidance, which is always difficult when patients want to know what to do … it's a very personal, very familial decision for the patient … I generally say these are the risks to you, these are the possible outcomes, and these are the risks of a procedure. And a procedure likely carries less risk than continuing a twin pregnancy. And ultimately, she was able to make the decision.”

The patient decides to move forward with the reduction procedure. 

Reflecting back, Dr. Hopkins shared, “What I've learned practicing high-risk OB is when you face a situation like this with a patient, it is impossible to know what decision that you would make if you were in that clinical situation … So just taking a step back and not necessarily trying to put yourself in the patient's shoes, but just stepping back and giving the information and just listening to the patient. I think as high-risk obstetricians, we're often the ones who have these stories and who see these patients, whether we're political or not, that's a life-saving procedure for us many times.”