Superfetation

Superfetation is the fertilization and subsequent development of an ovum when a fetus is already present in the uterus, a result of fertilization of ova during different ovulatory cycles and yielding fetuses of different ages. (Superfecundation, remember, is the fertilization of different ova within the same cycle.)

In other words, you can be pregnant and conceive a second child. Or, as in this recent case, you can be pregnant with twins and conceive a third child.

Superfetation is extremely rare in humans. There are only a handful of cases reported in the medical literature, most with a difference of three or four weeks between fetuses. The babies are typically delivered together.

The case of the Italian woman who claimed to have conceived triplets three months into her singleton pregnancy impressed even medical professionals, although it turned out to be nothing more than a hoax.

So if you're disappointed after your first ultrasound that you're not carrying twins, take heart - the possibility is not completely ruled out.

Comments

[kurt]

All this talk about babies......should we be expecting an announcement soon?

(isn't that terrible!? Me forcing your hand on your blog. Feel free not to post this one. But if you are expecting...congrats!)

[The Other Pete]

So what's with all this interest in pregnancies? ;-)

[The Other Pete]

Ha. I didn't even read Kurt's comment until after I'd posted my comment.

[Martina]

Pregnancy interests me because of my professional and (past, not current) personal experience with it.

That's it, sorry. But if I were pregnant, the Internet would be the first to know.

[sheri]

Please reassure me that being 35 weeks pregnant I can't possibly get pregnant right now because surely I would have a heart attack!

[Martina]

Sheri, as long as you've been using contraception throughout your pregnancy you should be fine.

[sheri]

Uh oh.....

[sherry huntley]

don't know about 2 different pregs but my mother-in-law had a miscarriage and gave birth to a 8 lb baby 4 months later. and they said she was only 2 mo at the miscarriage.

[Trisha Ferrell]

=] i am proud to say that i AM one of those rare cases. we were conceived two weeks apart.

[Antoinette Roberts]

I guess I am the 11th case. My girls were born on 11-06-1993. When I was 4 months pregnant, I was having pains, I went to the hospital and was given an ultrasound. The tech casually said,"Oh you have twins huh?" I said, "No! at least not the last time they checked." He said let me do some tests. He said I was gestationally 3 weeks pregnant with one when I got pregnant with the other one. They were born on the same date and the one who I got pregnant with last was considered premature. They were born 3 weeks early which I was told is normal for twins. So in essence, this would make the second twin be like 6 weeks early. So can someone answer this for me, are they twins because they were born at the same time or just regular siblings?