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).
Birth Order and Twins
The babies' order of birth is determined by their position in the womb, which can change throughout pregnancy. In some cases, which baby is born first depends on how the mother delivers; the order might be switched if the mother had a Cesarean section rather than vaginal delivery.
Although identical twins have the same genes, they don't always look the same. This is because children's health and development are shaped not only by genes but also by experiences in the womb and after birth. For example, a twin who gets less blood from a shared placenta might weigh less at birth.
Once the babies are large enough to stay in one position in the womb, the twin lowest in the uterus is known as Baby A and the one furthest from there is Baby B, according to the Stanford Medicine News Center. In the majority of vaginal births, Baby A is born first.
Most twin, triplet or more babies will be slightly different in size, but sometimes one baby is significantly smaller than the other/s. This is called 'selective' growth restriction (sFGR).
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.
What's a 'normal' weight for a multiple? About half of all twins weigh at least 5½ pounds at birth. (Below 5½ pounds, or 2,500 grams, is considered a low birth weight, with a higher potential for complications.)
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.
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.
A parasitic twin is an identical twin that has stopped developing during gestation, but is physically attached to the fully developing twin. The fully developed twin is also known as the dominant or autosite twin.
Fraternal (DZ) twins may have inherited different genes from their parents that cause them to grow at different rates in the womb. DZ twins are as genetically similar as non-twin siblings. Non-twin siblings can have very different birth weights. This might explain why some DZ twins have very different birth weights.
Another study found that identical twins ended up with virtually identical body weights as adults, whether they were reared apart or together. The study indicated that childhood experiences played essentially no role in determining variations in the weights of individual adults.
Severe Fatigue
Extreme fatigue is the most commonly reported complaint during pregnancy with multiples. Sleepiness, lethargy, and exhaustion during the first trimester can be enhanced because the body is working overtime to nurture more than one baby.
The gene versions that increase the chance of hyperovulation can be passed down from parent to child. This is why fraternal twins run in families. However, only women ovulate. So, the mother's genes control this and the fathers don't.
Identical (monozygotic) twins happen when a single egg (zygote) is fertilised. The egg then divides in 2, creating identical twins who share the same genes. Identical twins are always the same sex, so if your twins are identical, you'll have 2 girls or 2 boys.
OBJECTIVE: By convention, twins are labeled as twin A or twin B at the time of birth, depending on their birth order. However, antenatally twins are labeled as A or B according to their location relative to the birth canal. Antenatal labeling is usually established by prenatal ultrasound.
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.
While men can carry the gene and pass it on to their daughters, a family history of twins doesn't make them any more likely to have twins themselves. 3 But, if a father passes on the "twin gene" to his daughter, then she may have a higher chance than normal of having fraternal twins.
The first wife (died ante 1770), of Feodor Vassilyev (b. 1707–c. 1782), a peasant from Shuya, Russia, gave birth to 16 sets of twins.
These standard charts may not describe optimal weight gain patterns because recommended delivery gestational age for twins is between 37 and 42 weeks with average twin birth weights ≥2500 g to reduce mortality and morbidity.
While 40 weeks is the full gestation period of the average pregnancy, most twin pregnancies are delivered at approximately 36 weeks (range 32-38 weeks depending on the type of twin pregnancy).
The average weight of twins is 2.5kg.
Your Twin Babies at 35 Weeks Pregnant
Right now, your babies are almost at birth size and weight, measuring around 18 inches from top to toe, and weighing anywhere up to 5 or 5.5 pounds, which is around the size of a small honeydew melon!