For women born 1870-1899, moms of twins averaged reproductive spans of 14 years 11 months versus 14 years for singleton moms. Both results were statistically significant.
Longer lives
When analyzing the data by gender, the researchers found that female identical twins lived, on average, about 63.4 years, whereas female fraternal twins lived about 61.4 years and the general Danish female population lived about 58.8 years, Sharrow said.
They're also more likely to have health problems later in life, like high blood pressure. More than half of twins and nearly all higher order multiples weigh less than they should at birth.
They are associated with an eight to tenfold increase in the perinatal mortality rate,2 mainly because 40-70% of twins are born preterm.
Analysis shows that twins have lower mortality rates for both sexes throughout their lifetimes.
Using the family-based adult sample, no differences in IQ scores were found between twins and their singleton siblings.
At age 7, the mean IQ score of twins was 5.3 points lower than that of singletons in the same family, and at age 9, the score was 6.0 points lower. The lower intelligence of twins in childhood may partly be a consequence of the reduced fetal growth and shorter gestations of twins, say the authors.
One placenta and one amniotic sac.
This is the riskiest and rarest type of twin pregnancy. Fetal complications can arise due to tangling of the umbilical cords or an imbalance in nutrients, blood or other vital life supporting systems.
Most twins are born healthy. A twin pregnancy can mean a higher chance of health complications so you'll need extra check-ups. Twins that share a placenta or inner sac need to be checked more closely. It's good to know whether twins are fraternal or identical for health reasons later in life.
Being pregnant with multiples doesn't necessarily mean that your pregnancy will be problematic. However, women carrying multiples do have a higher chance of developing complications such as high blood pressure and preterm labor. For this reason, all multiple pregnancies are considered high-risk.
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.
Twins on the average seem to have lower IQs than singletons. The best estimate for this group difference is 4.2 IQ points (less than one-third of a standard deviation), with a great divide between study outcomes of less vs more recent birth cohorts (5.1 vs 0.5 IQ points, respectively).
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.
Identical twins live longer, possibly because they have a BFF from birth, according to researchers from the University of Washington, Seattle, WA. Furthermore, this effect is greatest in male identical twins, according to results from their recent study, published in the journal PLOS ONE.
Risks and Benefits of Twins Sleeping Together
1 Multiples who are co-bedded seem to sleep better, gain weight better, have fewer episodes of apnea and bradycardia, and (as long as they're about the same size), keep each other warm.
Identical twins share a particularly intense bond. They are the result of one fertilized egg splitting into two, giving them identical DNA. (Fraternal twins are the result of two separate, genetically different fertilized eggs.) As a result, identical twins are as close as two people can be.
The Yorubas believe twins bring good luck and riches, though many do not appear to remember this when their wives give birth to twins. People believe that, depending on how they are treated, twins can bring either fortune or misfortune to their families and communities.
Twins and other multiple-birth individuals can suffer from much deeper and troubling loneliness than single-born individuals. Separation anxiety, which often begins at birth, is the underlying cause of loneliness for twins.
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.
If a woman's sister has fraternal twins, she is about 2.5 times more likely to have twins herself. If a woman's mother has fraternal twins, she is about 2 times more likely to have twins. This is why we often say the “risk” for having twins comes from the mother.
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 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.
Twins will have better communication skills and less sibling rivalry than other children, a study shows. 'Multiple' siblings will have closer bonds than siblings of different ages and are likely to be best friends until adulthood, experts say.