In addition, previous studies have shown that first-born twins are, on average, taller and heavier than second-born twins until adolescence (Silventoinen et al., 2007; Pietiläinen et al., 2002).
Which twin is older? The oldest twin is the one who is born first. It doesn't matter whether twins are born vaginally or by C-section; the first one out of the womb is considered the oldest. This may be the baby who was labeled baby A during the ultrasounds, but it might not if the other one makes it out first.
Most often, fetuses known in utero as twin A are also first born and thus retain their label. However, this is not always the case, such that the twin A newborn was previously labeled twin B in utero and vice versa.
Despite the clinical impression that firstborn twins do better than second-born twins, recent reports have shown no difference in perinatal mortality between them. In order to evaluate differences in twins, more sensitive means than perinatal deaths are necessary.
In the majority of vaginal births, Baby A is born first. But occasionally the twins switch positions at the last minute, and Baby B emerges first, as further noted by the Stanford Medicine News Center. Still, the birth order is relatively straightforward.
Monoamniotic-monochorionic Twins
This is the rarest type of twin, and it means a riskier pregnancy as the babies can get tangled in their own umbilical cords.
However, for a given pregnancy, only the mother's genetics matter. Fraternal twins happen when two eggs are simultaneously fertilized instead of just one. A father's genes can't make a woman release two eggs.
As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood.
Once the cervix is open, each baby will have its own pushing stage. This means you will have to push twice, but the majority of the time the second twin is born much more easily than the first.
Physical Dominance – As would be expected, the stronger, bigger twin is the physically dominant. This is a theme that is seen in almost all of nature. It is simply a natural pecking order.
Depending on where they implant, one twin may get a smaller share of the placenta than the other, resulting in less blood flow and nutrition to one fetus, and more to the other. This is called unequal placental sharing. As a result, the twins may grow differently.
People over 30, and particularly those over age 35, are more likely to conceive twins. 4 This is because the level of follicle-stimulating hormone (FSH) rises as birthing parents get older. FSH is responsible for the development of eggs in the ovaries before they are released.
For a given pregnancy, the odds of conceiving fraternal twins are only determined by the mother's genetics, not the father's. Fraternal twins happen when two eggs are simultaneously fertilised instead of just one.
The longest interval between the birth of twins is 90 days, in the case of Molly and Benjamin West, dizygotic (fraternal) twins born in Baltimore, Maryland, USA to parents Lesa and David West (all USA) on 1 January and 30 March 1996.
Both results were statistically significant. Moms of twins also were older at the time of their last birth. The age at last birth averaged 39.7 years for women born before 1870, and 36.2 years for women born during 1870-1899. Moms of twins had their last births 4.8 months later and 14 months later, respectively.
It's a common misconception that twins skip a generation in families. There is absolutely no evidence, other than circumstantial, that twins are more likely to occur every other generation.
Many authorities recommend that monoamniotic twin pregnancies be delivered by elective cesarean as early as 32 to 34 weeks of gestation due to the risk fetal demise secondary to cord entanglement. Continuous electronic fetal monitoring of both fetuses is required throughout labor and delivery.
You may have heard that being pregnant with twins means an automatic C-section, but that isn't always the case. When it comes to twins these days, about half come into the world vaginally.
The median twin-to-twin time interval was 19 min (range 2–399) with 217 (41.2%) of the second twins being born within 15 min, 143 (27.1%) second twins were born within 16–30 min, 70 (13.3%) within 31–45 min, 37 (7%) within 46–60 min and 60 (11.4%) after 60 min.
Fraternal Twins Boy and Girl
Since conception happened for each egg, each egg carries the sex chromosome of the father. A girl has XX chromosomes while a boy has XY chromosomes. A boy-girl combination is the most common form of these kind of twins.
Twins and triplets often don't have a chance to reach a healthy weight before they're born. While the average single baby weighs 7 pounds at birth, the average twin weighs 5.5 pounds. Triplets typically weigh 4 pounds each, and quads weigh 3 pounds each.
The reason for this is biological feedback. If one twin feels that they are not getting enough nutrients, their body will start to take in more from your placenta. If the other baby does not react the same way, they may grow more slowly because their body did not react the way the other baby's did.
According to The American Society for Reproductive Medicine, women who are fraternal twins have a 1 in 60 chance of having twins, and men who are fraternal twins have a 1 in 125 chance of fathering twins. It was previously believed that identical (monozygotic) twins were random — not genetic.
Yes, some types of twins are hereditary, meaning that twins run in families. Heredity on the mother's side ups a couple's odds of conceiving fraternal twins. Fraternal twins are two babies from two different eggs that were released from the ovaries simultaneously.
Is there a third type? Traditionally, the science around twins has taught that identical and fraternal are the only two types. But a third type might exist, called polar body or half-identical twins.