What Percentage of Embryos Implant?

"Implantation Succeeds More Often Than It Fails"

Dear Fr. Bloom,

This is hardly scientific, but here are my arguments that, in a normal, natural pregnancy, implantation succeeds more often than it fails. (This is in response to some letters on your website.)

1) For my two first pregnancies, I became pregnant (and the baby implanted successfully) the very first month it was possible. (In other words, to be blunt, the first month when there was sex without birth control.) Even for this, my third, when I am 37 and my husband just had a vasectomy reversal (after 13+ years!) , we became pregnant in just the third month of possibility. There were factors in the other two months that made things more problematic, too, like my husband traveling away from me during the fertile period, and me having the flu twice.

2) 80% of women who are sexually active and not doing anything to prevent pregnancy, get pregnant in the first year. Most of them get pregnant in the first three months. (I had a book with figures on this, but don't now. I looked all over the internet for statistics, but couldn't find them. I'll continue researching, and if I find more specifics, I'll get back to you.) When we're talking pregnant here, we are obviously talking about being aware of being pregnant, which would not be until the baby is implanted. Implantation takes place at about Day 10 of life, at least four days before a woman misses her period.

The 80% figure could still mean that for ten out of twelve months, the babies are conceived, but fail to implant. (Ten infertile months would be 83%.) But this is extremely unlikely since other factors besides implantation are involved, such as whether the woman actually ovulated that month, whether intercourse occurred at the fertile time, whether her mate is fertile, and so on. But the fact is that most women get pregnant in their first three months, which would allow for only 67% of months to be infertile.

What I'd like to know, though, is how many of sexually-active women who are not trying to prevent pregnancy actually get pregnant in the very first month. I wouldn't doubt that when a healthy woman is actively trying to get pregnant, by noting her fertile periods and making sure to do the right things then, the chances of getting pregnant (and implanted) that first month are very high indeed. I am thinking that the Couple to Couple League or another NFP group might have some statistics on this.

3) A book I do now have in hand, The Complete Book of Pregnancy and Childbirth, by Sheila Kitzinger, published in 1989, says that blastocysts (early embryos) fail to implant in the uterus at rates estimated between 1 in 3 and 1 in 10. So, before the IVF technology was widespread, the figures for failure to implant were considered much lower. But after all, in how many totally healthy women would the issue even come up? Most women who have had no infertility problems are not so anxious to know, and would not be tracked carefully.

4) It's obvious that in vitro fertilization is going to cause more problems with implantation than natural means. First off, we're dealing almost entirely with women whose fertility is pretty radically upset, or they wouldn't be trying such an expensive, invasive procedure. Secondly, perhaps the babies thus conceived are more fragile--they are babies that would not otherwise even have been conceived. Thirdly, the mother is going to be under great stress, and stress is going to reduce her body's ability to accept the little one. (She is almost indubitably in stress because she very much wants a baby, is spending huge money and going through lots of medical procedures to make it happen, and still her odds of getting pregnant are quite poor.) True, doctors try to make up for all this by putting the right hormones in, timing matters perfectly, etc,, but as close as they seem to have come to godlike powers, God still has them beat!

Of course, the issue is not whether in normal life, many embryos do fail to implant. The issues are whether it is okay to separate married sex from making babies and whether it's okay for us to disrespect life to such an extent as to make it even more likely that the babies, however tiny, will die. (Simply by creating more babies, even if implantation statistics are the same for natural conception and IVF,. we will also cause more deaths.) .

I sure wish there was something we could do to stop IVF from being so widely accepted and used. It saddens and amazes me that most people think this is normal and okay, even when babies are living in cold storage for years, or having their tissues used rather than wasted (Some of these babies are considered just waste products of the process), or being eliminated as no longer desirable, or being implanted in large numbers to have six babies die at once. ( A friend did IVF, and had six embryos implanted. All died. This was her second time, with the same results as the first. Six more babies wait in cold storage, in case she can get the money together to go through it all again. This is the stuff of my nightmares.) I have some idea of how much a mother can be obsessed with the desire of having a baby, but having it conceived in married union seems so immensely superior. If that is not possible, one has to wonder if God has another plan for that couple. Adoption, maybe? Some times one just has to accept not having what one most desires.

You may quote my letter, but I prefer you leave off my name or e-mail address, as I've put some pretty personal information in here.

Thanks,

A

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Dear A,

Thank you. What you say makes a lot of sense - and is so important. I will upload it (w/o you name) next time I update. I was recently reading how in the slavery debate, Lincoln argued that another human must never be considered as a means to some end, but as an end himself. As you say, it both amazing and sad that we have come to such a point with our tiniest fellow human beings.

Prayers always. Keep up the good fight.

Fr. Bloom

See also: Embryonic Stem Cell Statement (Catholic Leadership Conference)

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