Is it true that late implantation leads to a higher risk of miscarriage? Is it possible that was the cause of my miscarriage in my last pregnancy?
It's true that a few studies have found a higher risk of miscarriage in pregnancies with implantation occurring more than eight to 10 days after ovulation. This is probably the origin of the rumor that late implantation means a higher risk of miscarriage, as these studies did receive some news coverage when they first came out.
What exactly the finding means, however, is debatable. Late implantation by itself is not likely to be a direct cause of miscarriage. One theory is that embryos with chromosomal abnormalities, which are known to be likely to miscarry, may also be more likely to implant later because of issues related to the chromosome problems. Another theory is that some factor in the uterine lining could cause problems during implantation and that this would lead to miscarriage, but researchers are still studying the matter.
In either case, the timing of implantation isn't under anyone's control -- and again, there is no evidence that late implantation by itself would be a cause of miscarriage. Still, if you have menstrual irregularities or if you have been struggling to conceive, however, it makes sense to talk to your doctor to see if there are any problems that could be interfering with your ability to get pregnant.
Macklon N. S., J. P. M. Geraedts and B. C. J. M. Fauser. "Conception to ongoing pregnancy: the ‘black box’ of early pregnancy loss." Human Reproduction Update, Vol.8, No.4 pp.333-343, 2002
Norwitz, Errol R., Danny J. Schust, and Susan J. Fisher. "Implantation and the Survival of Early Pregnancy." N Engl J Med. 2001 Nov 8;345(19):1400-8.
Wilcox, Allen J, Donna Day Baird, and Clarice R. Weinberg. "Time of Implantation of the Conceptus and Loss of Pregnancy." N Engl J Med. 1999 Jun 10;340(23):1796-9.