Twin 101

We get MANY questions regarding twins and this pregnancy, so hopefully this will answer some of the questions that you may have! Keep in mind that this is VERY general and basic, and that I'm not posting about random exceptions. So, on to Twin 101...

Fraternal (Dizygotic) and Identical (Monozygotic). (Our girls are identical or monozygotic.)
-Fraternal twin pregnancies result when two eggs are fertilized by two sperm.
-Identical twin pregnancies result when one egg is fertilized by one sperm, and then the fertilized egg splits in two.

Amniotic Sacs and Placentas. (Our girls are diamniotic/monochorionic.)
-Fraternal twin pregnancies are much like a singleton pregnancy here, in that each baby has it's own amniotic sac (diamniotic) and it's own placenta (dichorionic).
-Idenitical twin pregnancies can vary quite a bit here. Each twin can have their own amniotic sac (diamniotic) and their own placenta (dichorionic), each twin can have their own amniotic sac (diamniotic) and share one placenta (monochorionic), or the twins can share one amniotic sac (monoamniotic) and share one placenta (monochorionic).

Gender. (Our girls are GIRLS!!!)
-Fraternal twins can be two boys, two girls, or a boy and a girl.
-Identical twins must be either two boys or two girls.

Genetics of the Twins. (Our girls are genetically identical.)
-Fraternal twins are genetically as similar as any other siblings.
-Identical twins are genetically identical.

Do Twins Run in the Family? (No, but in our situation, this doesn't matter.)
-There is a genetic link in the families of some fraternal twins. The mother releases more than one egg during ovulation.
-There is absolutely no genetic link with identical twins. It is a complete fluke.

Common Risks and Complications with Twin Pregnancy.
-Pre-term labor. Due to this, and other reasons, a mother pregnant with twins is commonly put on bedrest before term and is monitored closely.
-Twin to twin transfusion. This is almost solely in identical twins. It occurs when a blood vessel in the placenta is shared by the twins. This is very dangerous and requires either laser surgery (early in pregnancy) or delivery (later in pregnancy).
-Elevated blood pressure. This can lead to pre-eclampsia. (I had pre-eclampsia with Benton, so I am at higher risk for having the same issue again.)
-C-Section. (We have already chosen this option for our delivery.)

Other Info.
-It is recommended that a woman pregnant with twins gain between 37 and 54 pounds. (They have recommended that I gain 50 pounds.)
-Full term for twins is 38 weeks, though they generally don't let monochorionic identical twins go past 37 weeks. (They have told us to expect and hope for delivery between 36 and 37 weeks.)

Hopefully this answers most of the questions that people ask us!