The funny thing is, this thread does share several important traits with your typical episode of House: 1) puzzling condition that defies simple diagnosis, 2) hypotheses of people lying and screwing up, and 3) hypotheses of exceedingly rare conditions. The only thing we need now is a cane and a bottle of Vicodin, and we’ll be all set to figure this one out.
^^^^understandably
And please, for the love of God, either
A) Abortion
or
B) Adoption
since you guys don’t seem interested in parenting.
Good luck, don’t do anything you will regret, and don’t do anything illegal.
How about c) reliable birth control from now on? No offence, honey, but if you’re patently uninterested in parenting, reliable safe birth control methods are a lot easier than this childbirth thing.
I’m pumping milk for a premie in the hospital. I didn’t expect it to have the same ovulation/menstruation suppression that breastfeeding does, but I wasn’t expecting a return to fertility quite so quickly!
I’m sure you and your wife know this, but let’s remind our studio audience that breastfeeding, even exclusively, does NOT provide ovulation supression good enough to be considered birth control. Women today are far too well fed for this old wives’ tale to hold true - she can ovulate at any time and become pregnant without ever getting a period!
DAYUM! I’ve been a laystudent of human fertility for years and I’ve never heard of this. Huh. How rare is it, do you know? I can only find a handful of human cases reported in papers on PubMed, and most of those seem to be fertility treatment related. Yay, I have something new to study! 
Well, if she is indeed pregnat, it is already too late for birth control (this time around).
Yeah, but evidently it’s an ongoing problem. One does hope for future improvement.
“menstrating during end of pregnancy” : OP
Aside from the spelling, you seem to have a tenuous grasp of physiology. Maybe you are speculating that your girlfriend was ovulating during the end of pregnancy. Menstruation is something totally different. This is not the forum for us to be judgmental - although many of us are apparently trying very hard not to be - but in order to be a responsible sex partner, I’d recommend a crash course on the female reproductive cycle.
Gestational age doesn’t mean different dates of insemination, some embros mature more slowly due to a number of possible problems. Even idential twins can have different gestional ages.
The parents misunderstood what the doctor explained poorly.
The question of the 17 week embryo being seen on ultrasound, doesn’t ring true. Hereis a photomicrograph of a 17 day embryo. Even it it were big enough to see, it wouldn’y be recognizable as anything but a blob of tissue.
I’m afraid the you and/or your GF misunderstood the doctor.
Ancient Greeks and their myths had the Gemini twins described as being from different fathers.
I’d agree, but…how then how are those who generated this picture so sure they’re looking at an embryo themselves???
- Jinx
Jinx, I’d say the answer to your question most likely is, that it was proven as the pregnancy progressed.
I don’t know about anyone else, but there was no way on earth that I would have had sex 2 weeks after giving birth vaginally. OUCH!!! Besides, as the other posters said, it would be virtually impossible to see anything on an ultrasound at 2 weeks gestation. What is possible is that there is a piece of retained placenta in her uterus and that is what the doctor saw on the ultrasound and your girlfriend misheard him. I think you need to go see this doctor for yourself and find out exactly what is going on. Please post back when you uncover this mystery! I’m intrigued.
Eh, maybe. If she’s young (as sounds likely), not taking care of a newborn and had an uncomplicated birth with no episiotomy, she could heal that quickly. Never underestimate the power of teenage hormones.
Not that I disagree, but that image says that it’s of a mouse embryo.
It’s a mouse embryo at 7 days, which is the same level of development as a human zygote at 17 days. The two are virtually indistinguishable - here’s an 18-day human.
Ahh, got it. I’ll just invoke the Caffeine Defense 
Can we get an update? Retained placenta? Some sort of communication problem between your gf and the doc? Double uterii? Alien involvement? Secretly trolling? By now you should know what’s up in there…
The OP has been banned. I guess we’ll never know.
Actually, he’s been suspended. Orange Juice hauss is claiming Creepy Abortion hauss is his brother posting under his username.
So which one was it who wanted to feign insanity to get out of child support?
(Boy, this is better than soap operas any day…)