Identical twins are created when a single fertilized egg splits and two fetuses develop from it. Identical twins may share both a placenta and amniotic sac, or have individual amniotic sacs while still sharing the same placenta.
Technically, a twin can hide out in your uterus, but only for so long. Its not unheard of for a twin pregnancy to go undetected in early ultrasounds (say, around 10 weeks).
Can single pregnancy become twins?
Identical twins occur when a single embryo, created by the union of a sperm and an egg, divides into two embryos. Each embryo is monozygotic, genetically identical, and both will be the same sex.
How late can twins be detected?
Its possible to see twins (or more) on an ultrasound at around six weeks, though one baby may be missed at this early stage. Sometimes a heartbeat is seen in one sac, but not in the other. Rescanning in a week or two may reveal a second heartbeat, or the scan may show that one sac is growing and the other still empty.
Is it possible to have twins and not know?
Ultrasound can tell us a lot about a pregnancy, but its not always perfect. This is particularly true in the early months of pregnancy. Though it is rare, it is possible to have a hidden twin that is not visible during early ultrasound screenings.
Can you have twins but only hear one heartbeat?
In many cases there will be multiple amniotic sacs too, although identical twins may be sharing one. You will usually be able to listen to each babys heartbeat and to take a close look at them on the screen while they are being measured and examined.
Can twins be detected at 7 weeks?
Today, twins can usually be diagnosed as early as six to seven weeks of the pregnancy, he adds.
What are the odds of having twins?
Its estimated that 1 in 250 pregnancies results in twins naturally, and there are two ways to conceive them.
How do I know that I have twins?
Many twin pregnancies are discovered by ultrasound. Your doctor may suspect you are pregnant with more than one baby when checking your babys heart rate or having alpha-fetoprotein levels tested. If your doctor suspects you may be pregnant with multiples, they will likely recommend you go for an ultrasound.
Does your belly get bigger with twins?
If youre expecting twins or higher-order multiples, you could also possibly start to show before the end of your first trimester. Your uterus must grow larger to accommodate more than one baby. So whereas someone expecting a singleton may not show until after 3 or 4 months, you might show as early as 6 weeks.