Fact-checking the Prenatal Science in Bridget Jones’s Baby

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Photo: Courtesy of Universal Pictures/Miramax

Warning: Spoilers ahead.

In Bridget Jones’s Baby, Bridget (Renée Zellweger) finds herself unexpectedly pregnant at the age of 43 after having one-night stands with handsome dating guru Jack Quant (Patrick Dempsey) and old flame Mark Darcy (Colin Firth) in quick succession. Early on, Bridget visits her doctor (Emma Thompson) to find out the paternity of the baby via amniocentesis, but chooses not to have the procedure when she learns there’s a risk of miscarriage.

This means Bridget has to wait until the baby is born to find out who the father is, thereby forcing both Jack and Mark to be active participants in her pregnancy. Is this just a convenient narrative device to set up the film’s love triangle, or is Bridget’s decision rooted in science? We called up a doctor to find out.

There are basically two ways of doing paternity tests during pregnancy, says Dr. Jacques Moritz, affiliate associate professor ob-gyn at Weill Cornell. They are CVS (chorionic villus sampling) and amniocentesis. CVS is considered an invasive procedure and can be done about ten weeks into the pregnancy, making it the earliest available chance to determine paternity of a fetus. It is done by removing cells from the placenta, and is usually painless.

Amniocentesis, which figures so heavily into Bridget Jones’s Baby, is a procedure in which a large needle is inserted into the belly to remove a small amount of amniotic fluid. It is usually performed between 14 and 16 weeks into the pregnancy, and is most commonly used to test for chromosomal abnormalities such as Down syndrome.

Both procedures carry small risks of miscarriage — CVS results in miscarriage about once in 100 times, while amniocentesis results in miscarriage about once in 1,600 procedures, according to the most recent study. (Previous estimates for pregnancy loss from amniocentesis were a lot higher.) One in 100, or even 1 in 1,600, when it’s your pregnancy, isn’t really very low at all: It’s actually fairly high!

And those risks are very real, so these procedures are done only when necessary. Dr. Moritz says that CVS and amniocentesis performed for paternity is “always for legal issues” — like when there’s a court order. So, yeah, Bridget probably wouldn’t get an amnio to find out which hunk is the father of her baby.

Fact-checking the Prenatal Science in Bridget Jones’s Baby