Many scientists and doctors have discovered that progesterone, in the natural form, protects the fetus from miscarriage and that women who have a history of failed pregnancies start using progesterone for preventing miscarriage.
If a woman has had four or five miscarriages in the first six or eight weeks of a pregnancy, this can be due to luteal phase failure, says Dr. John Lee. Progesterone is needed to facilitate implantation and to prevent rejection of the developing embryo, but the follicle may not respond to the ovum. Dr. Lee's recommendation is: "Wait till you ovulate, and then four to six days after possible conception do a blood test (for HCG) to see if you're pregnant. If you are pregnant, start the progesterone, that way you will increase your chance of having a healthy baby." Blood tests for pregnancy tend to be positive within seventy-two hours of conception.
One of Dr. Lee's important findings is that there is an immune-suppressing effect in the uterus from higher doses of progesterone. This is important, because when conception takes place, half of the baby's chromosomes are from the mother and half from the father. That makes the baby's tissue DNA different from the mother's because of the contribution of the father. If there's not a good tissue match, the difference may create tissue rejection. But this doesn’t happen with pregnancy because of the progesterone response in the uterus. By giving more progesterone after conception, you increase the likelihood that the baby will survive.
Looking at the problem from another perspective, Dr. Lita Lee informs us that "after conception progesterone prevents miscarriages resulting from excess estrogen."
It is a fact that if a pregnant woman produces too much estrogen, her embryo can be suffocated (hypoxia). Dr. Lita Lee cautions that during the ninth week of pregnancy, a woman can lose her baby if she is a "high estrogen producer and/or [is] consuming commercial meat, poultry and dairy products containing synthetic estrogen (DES)." However, she goes on to say that natural progesterone "has been known to protect against the toxic effects of excess estrogen, including abortion." Make certain, if hormones are prescribed during pregnancy, that they are not the synthetic progestins or estrogens but the natural micronized products. We now know that artificial hormones can be dangerous to the fetus during pregnancy.
Dr. John Lee stresses that synthetic compounds cannot be efficiently "excreted by one’s usual enzymatic mechanisms. Despite their advertisements, synthetic hormones are not equivalent to natural hormones."