Eating (McDonald's) French Fries After IVF?

If you've been part of the IVF community, you've probably seen a few dozen posts of women making the drive to McDonald's after their embryo transfer. Is there something about embryo transfers that makes everyone crave a greasy burger and fries? Do fertility clinics hand out coupons valid only within an hour of transfer? No. Couples make the drive because (1) it's a fun tradition and (2) there are persistent rumors that fries after transfer boost pregnancy rates.

French fries or fertility fries?

So what is it about fries that could supposedly help embryo implantation? The fries themselves? The oil? The seasoning? I couldn't find any specific mechanism, but plenty of online discussions claiming success -- alongside just as many claiming McDonald's causes infertility via pesticides and chemicals. This tradition isn't new either; some posts date back to 2006. There's only one problem with this delicious theory: a total lack of scientific evidence. I looked for evidence tied to specific ingredients, the frying oil, the seasoning -- nothing. Plenty of unscientific claims exist, ranging from "fat makes your uterus stickier so the embryo has somewhere to nest" to "the salt draws the embryo closer to the womb." Unfortunately, that's not how bodies work.

How it all started

The tradition seems to trace back to doctors recommending patients at risk for ovarian hyperstimulation syndrome (OHSS) eat salty foods after egg retrieval. OHSS develops in about 1-10% of women undergoing IVF, causing fluid accumulation around the ovaries and abdominal cavity, which is painful. That fluid needs something to bind to so it can move out of the body, and salt does exactly that -- which is why salty food is often recommended after stimulation. From there, it's easy to imagine how "eat something salty" turned into "eat fries every day from retrieval to transfer," someone got pregnant, told her friends what she did differently, and a tradition was born.

Fries for frozen embryo transfer?

Given that salty foods can genuinely help with OHSS, fries could plausibly help women doing a fresh transfer. But what about frozen embryo transfers (FET), where the OHSS risk has already passed? Many people still swear by the fries even then. The original logic (fighting OHSS) doesn't apply to FET at all -- it just generalized into "a recipe for success." As you now know, that's not accurate. But it's a pretty benign habit either way: not the healthiest thing to eat, but it won't hurt your chances either.

Fact or fiction?

So do you need to drive to Mickey D's after transfer? There's no evidence eating fries benefits implantation in any way. Correlation isn't causation -- some women who ate fries got pregnant, but that doesn't mean the fries caused it. If you're craving fries after egg collection, go ahead, it might genuinely help with OHSS symptoms. Craving them after transfer? Order up, why not. And if you're just craving fries while trying to conceive generally, know it won't help in the slightest, but it won't hurt either. For most people, it's simply a fun tradition -- the picture of your feet in the stirrups followed by a McDonald's selfie is basically shorthand in the IVF community for "I just had a transfer." Nobody should stress if McDonald's is out of fries that day, or if they end up at Burger King instead.