Asian Americans and Native Americans have the lowest twinning rates. White women, especially those older than 35, have the highest rate of higher-order multiple births (triplets or more).
Africa has a high rate of twins born naturally from two separate eggs, and according to the study 80% of twins are now born either in Africa or Asia.
The percent of people who are twins differs by race and ethnicity. In the U.S., twins are most common in African-Americans (36.8 per 1000) and least common in Hispanic/Latino Americans (21.8 per 1000).
Birth rates for MZ twins are consistent among all races (about 4 per 1000); but the incidence of DZ twinning varies among races (8 per 1000, among Caucasians, 16 per 1000 among people of African descent, and 4 per 1000 among Asians).
Older women generally have a higher chance of conceiving twins. A 35 year old woman is about 4 times more likely to have fraternal twins than a 15 year old! That is because they are experiencing some hormonal changes as they near menopause. This could encourage their body to release more than one egg during ovulation.
This is why fraternal twins run in families. However, only women ovulate. So, the mother's genes control this and the fathers don't. This is why having a background of twins in the family matters only if it is on the mother's side.
Age. According to the Office on Women's Health , women who are aged 30 years or older are more likely to conceive twins. The reason for this is that women of this age are more likely than younger women to release more than one egg during their reproductive cycle.
About one-third of twins are identical or monozygotic twins (when one fertilised egg divides in half). Two-thirds are non-identical or dizygotic twins (when two eggs are fertilised by different sperm). The chance of any woman having identical twins is one in 300.
Asian and Native Americans have the lowest twinning rates. Caucasian women, especially those over age 35, have the highest rate of higher-order multiple births (triplets or more).
Monoamniotic-monochorionic Twins
These types of twins share a chorion, placenta, and an amniotic sac. This is the rarest type of twin, and it means a riskier pregnancy as the babies can get tangled in their own umbilical cords.
The Science of Fraternal Twins. Mixed-gender twins are the most common type of fraternals, some 50 percent are boy-girl.
Factors that increase the chance of twins include: consuming high amounts of dairy foods, being over the age of 30, and conceiving while breastfeeding. Many fertility drugs including Clomid, Gonal-F, and Follistim also increase the odds of a twin pregnancy.
In Nigeria, a growing city called Igbo-Ora is known as the twin capital due to it having the highest rate of twin births in the world. The town is the home of the annual World Twins Festival, which celebrates the many twins that reside in their community.
The fertility rate in the United States in 2020 was 56.0 per 1,000 women ages 15-44. Of all live births in the United States during 2018-2020 (average), 23.7% were Hispanic, 52.1% were white, 15.2% were black, 0.8% were American Indian/Alaska Native and 6.8% were Asian/Pacific Islander.
A big reason for all those twins is an increase in medically assisted reproduction, including in vitro fertilization, ovarian stimulation and artificial insemination. Another reason is that women in many countries are having babies at older ages.
In fact, one British study tested ESP potential among identical twins and found that they were correct about 25% of the time, the same as any other siblings. There is one particular power though which twins possess, longevity. Fraternal twins live longer than singletons and identical twins longer still.
The increase is mainly due to increases in dizygotic, or fraternal, twins; rates of monozygotic, or identical, twins have remained about the same worldwide, with about 4 identical twin births per 1,000 deliveries.
It has been widely assumed that there has been an increase in twins over the years, largely attributed to fertility treatments. But the increase in the multiple birth rate means not just more twins, but also higher order multiples, such as triplets, quadruplets and the like.
You're more likely to have a vaginal birth if the first twin is in a head-down position. But there may be medical reasons why a vaginal birth is not recommended. If you have had a caesarean section before, for example, it's not usually recommended that you have a vaginal birth with twins.
A twin pregnancy with two placentas and two amniotic sacs is the optimal twin pregnancy, as each baby has its own nutritional source and protective membrane. One placenta and two amniotic sacs.
The authors of the study believe the reason twins live longer may be because of the social support they provide each other, and the psychological and health benefits that come with that social connection. "There is benefit to having someone who is socially close to you who is looking out for you," Sharrow said.
So, having identical twins is not due to genetics. On the other hand, fraternal twins can run in families. In fact, a woman that has a sibling that is a fraternal twin is 2.5 times more likely to have twins than average!
Many people believe twins skip a generation, but that's just a myth. The idea that twins skip generations likely comes from the fact that the genetic factors contributing to twins only come from the gestational parent's side.
Several factors for causes of embryo splitting were suggested, including maternal age, prolonged embryo culture, ovarian stimulation, and zona pellucida (ZP) manipulation [6].
Central to the Yoruba people's diet are plants with a tuber root, such as yam and cassava. Some residents and experts in Nigeria believe that, due to the high phytoestrogen content in these plants, women are more likely to release more than one egg at a time, which usually leads to twin pregnancies.