Pregnant and Pregnant Again: Superfetation


A pregnant woman in Arkansas who is due to give birth in December 2009 has discovered that she is also pregnant with a second child that appears to have been conceived nearly three weeks after the first. If true, she is experiencing a rare phenomenon called superfetation.

Superfetation is a condition in which a second fetus forms or develops in the uterus after another fetus has already been developing. This rare phenomenon appears to be common in some animal species, such as mice, rats, sheep, and marsupials, but extremely rare in humans. It can occur when the menstrual cycle continues through the pregnancy. When there are two separate occurrences of fertilization during the same menstrual cycle, rather than different cycle, it is known as superfecundation.

According to Dr. Karen Boyle, who spoke on “Good Morning America,” she could only find “about 10 reported cases” of superfetation. A review of the literature reveals this to be true, according to an article in the December 2008 issue of the Journal of Gynecology, Obstetrics, and the Biology of Reproduction (Paris).


Superfetation has been recognized for centuries. In the Talmud in Nidah 27a, it states that a woman cannot become pregnant and then become pregnant again; that is, superfetation is not possible. Yet in Yevamot 12b, the Talmud says that pregnant women should use contraception so her fetus will not become compressed or damaged if she becomes pregnant again. This implies that superfetation is possible. According to an article in the medical journal Harefuah (February 2008), superfetation has been recognized since the times of the ancient Greeks.

For our modern day mother, Mrs. Julia Grovenburg, whether she is truly experiencing superfetation will only be known after she gives birth and chromosomal and metabolic studies are conducted on the infants. Dr. Boyle told ABC News that superfetation can be dangerous for the younger fetus because the child could be born prematurely, which raises the risk of immature lung development and function. Because the fetuses appear to be less than three weeks apart, this complication and other risks fortunately may not present much need for concern.

ABC News, “Good Morning America” September 24, 2009
New York Daily News, September 24, 2009
Pape O et al. J Gynecol Obstet Biol Reprod (Paris) 2008 Dec; 37(8): 791-95
Rabinerson D et al. Harefuah 2008 Feb; 147(2): 155-58
Torat Emet,

Written by Deborah Mitchell



I have just found out I am pregnant with 1 baby 8 weeks 5 days old and one 7 weeks and 1 day old. And I thought for years I couldn't have children.
Congratulations! I hope wlll goes well with your pregnancy.