Why IVF Produces More Baby Boys Than Girls

Dawn Davenport

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Why are baby boys more likely to be conceived when using IVF?

Did you know you were more likely to have a baby boy when using IVF?

You are 3- 6% more likely to have a baby boy than a girl when using IVF to conceive. IVF increases the odds of a boy from 51 in 100 when conceived naturally to 56 in 100 with IVF. Up until recently, we have not known why. Recent research is shedding light on why exactly IVF produces more boys than girls, and suggest possible solutions.

A team of researchers in China found that female IVF embryos had a lower survival rate and higher rate of growth defects. These defects resembled symptoms of impaired X chromosome inactivation.

Males have an X and Y chromosome, while females have two X chromosomes. The extra copy of the X chromosome in females is switched off during early embryo development by an epigenetic process known as “X chromosome inactivation”. The researchers found that X chromosome inactivation was impaired in female IVF embryos.

Research now continues on how to correct this gender skew in IVF. One possibility being explored is supplementing the IVF growth culture with the epigenetic modifier retinoic acid. Research so far is only on mouse models, and not available for humans at this time.

“To the best of our knowledge, retinoic acid is not used in IVF procedures for humans,” Tian said. “It should be noted that there are some differences in the mechanisms of X chromosome inactivation between mouse and humans, so whether the X chromosome inactivation status is impaired in human IVF embryos needs to be further determined. In addition, risk evaluation is required before the clinical application of retinoic acid in IVF.”

Separate research has shown that when the IVF cycle includes intra-cytoplasmic sperm injection (ICSI), a process where a single sperm is selected and inserted into the egg manually by the embryologist, more girls are born. Clearly there is a lot we still do not know about gender and IVF.

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Did you know that you were more likely to have a baby boy with IVF?

29/06/2016 | by Dawn Davenport | Categories: Blog, Infertility, Infertility Blog | 4 Comments



4 Responses to Why IVF Produces More Baby Boys Than Girls

  1. Tina says:

    Hello,I am 37 yo and have a 4 years old boy with a successful IVF cycle(at his time 2012 was no PGD)…while he was 3yo we started another IVF cycle which I had one girl and one boy embryos with the PGD, but after the transfer of the 2 FEs I had miscarriage…Last February we had another IVF cycle with the PGD which we got 3 boys embryos( with great grades) and 5 girls embryos but all with chromosomal abnormality!! We transferred the 2 boys, and I got pregnant with twin boys at the beginning, then at 7 weeks one of the twin got splitted but didn’t survive and got shrinked..so now I am 10 weeks pregnant with my second boy and due on January 28,2018!! We want to have a baby girl with another IVF cycle, how can we increase the chance of having girl embryos with the next IVF cycle.
    Thanks

    • Dawn Davenport Dawn Davenport says:

      First, I’m so sorry for your miscarriages and so happy that you are now pregnant with your second child! We are not doctors and this is a good question for your infertility doctor. To oversimplify, all the woman’s eggs carry the X chromosome. The man produces X and Y chromosomes evenly. If the Y chromosome fertilizes the egg a boy embryo is created. If the X chromosome fertilizes the egg a girl embryo is created. (I realize that you already knew that, but it helps with my explanation.) The most common way of gender selection is to genetically test the embryos and to only transfer the preferred gender, which is what you have tried to do the last two IVF cycles. Anything you can do to have more mature eggs to retrieve in theory would increase the odds of having more eggs to fertilize, which in turn would increase the possibility that an X sperm will be successful. However, your doctor is probably already doing that and to be honest, your age is working against you. You might talk with your reproductive endocrinologist about doing an egg retrieval and freezing the embryos sooner than you want to try again just because you will be getting older and want to get as many good eggs as possible.

      I have heard of sperm spinning/sorting to separate the X and Y sperm. I haven’t done the research, but I don’t know how successful it is. Most infertility doctors that I’ve spoken with say that PGD is more effective at selecting gender so they prefer to use that technique. However, I haven’t spoken to that many docs and there is likely good research on the efficacy of sperm sorting.

  2. Carolyn says:

    This last cycle of IVF with frozen eggs produced 3 boys for us. One is still a “tot-sicle,” waiting to be born. Adding retionolic acid is an interesting idea. I’ll watch for more research on that topic.

    • Cc says:

      I’m just starting my research now on IVF. I see where you said it produced 3 boys have you had any yet? Are they positive they are boys? I want to learn everything before starting this journey
      Thank you so much for all the research and your stories.

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