Advancing maternal age. Women who are aged in their 30's and 40's have significantly higher chances of conceiving with twins. Younger women, especially those aged in their 20's, do not have as much chance. Having assisted reproductive technology, in particular taking medication which increases ovulation.
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.
It's usually possible to find out if you're having twins through your 12-week scan. At the scan, you should be told whether the babies share a placenta (meaning they're identical) or if they have 2 separate placentas (meaning they can be identical or not).
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.
Home pregnancy test positive earlier than “normal”
If you get a positive test, especially a really dark positive, days before your period is even due, that may be one of the early signs of twins! The more babies you're carrying, the higher and faster your human chorionic gonadotropin hormone (hCG) rises.
The twin gene is carried by the mother, meaning that it is her genes that determine whether someone may have fraternal twins.
Most cases of identical twins don't appear to run in families and instead seem to be a spontaneous occurrence, say experts. But there are some families with a larger-than-usual number of identical twins, suggesting there may be a genetic link.
Several factors for causes of embryo splitting were suggested, including maternal age, prolonged embryo culture, ovarian stimulation, and zona pellucida (ZP) manipulation [6].
If one identical twin has autism spectrum disorder (ASD), the other twin has a 76 percent chance of also being diagnosed with it. The numbers are lower for fraternal twins. The percentage of fraternal twins who each share an ASD diagnosis is 34 percent for same-sex twins and 18 percent for boy-girl pairs, Dr.
Identical twins are almost always the same sex, although there are some rare exceptions to this rule. Because identical twins occur when a single fertilized egg splits and forms two embryos, each embryo has the same chromosomes (usually, XX for girls or XY for boys).
The notion that twins always skip a generation is also a myth. The illusion may have arisen because men who inherit the gene from their mothers are unaffected by it ( they do not ovulate), but can still pass it on to their daughters, who, in turn, will have an increased likelihood of conceiving twins.
Do Twins Skip Generations? 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.
In 99.9% of cases boy/girl twins are non-identical. However, in some extremely rare cases resulting from a genetic mutation, identical twins from an egg and sperm which began as male (XY) can develop into a male / female pair.
They come from the same fertilized egg and share the same genetic blueprint. To a standard DNA test, they are indistinguishable. But any forensics expert will tell you that there is at least one surefire way to tell them apart: identical twins do not have matching fingerprints.
Identical (i.e., monozygotic, or MZ) twins share 100 percent of their genes, whereas fraternal (i.e., dizygotic, or DZ) twins generally share only 50 percent of their genes.
There are more twins in the “millennial generation” than any other generation, thanks partly to a twin boom in the '90s. The main reason was a new technology called in vitro fertilization, which in its early days frequently produced twins, triplets and other multiple births.
"[Two sets of] identical twins will not have identical offspring," says Professor Rodney Scott, head of medical genetics at the University of Newcastle. The only way we get identical offspring is when a fertilised egg splits into two cells. "Those identical cells grow into identical twins," says Scott.
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. If you have monoamniotic-monochorionic twins, your healthcare provider will monitor your pregnancy closely.
In pregnancies with one placenta and two amniotic sacs, you will definitely have identical twins. Additionally, when your babies share a placenta, there is a greater risk for complications, such as twin-to-twin transfusion syndrome.
Monozygotic (identical) twins will have the same blood type, with a few very rare exceptions. Dizygotic (fraternal) twins may have the same blood type, or they may have different types. Therefore, it may be concluded that twins with differing blood types are dizygotic, or fraternal.
Children who have an older sister with autism are more likely to also have the condition than are those who have an older brother on the spectrum. The risk is higher among younger brothers than younger sisters.
“Twin studies of major depressive disorder have showed that if one twin has the illness, a fraternal twin has an increased likelihood of developing the disorder and an identical twin's likelihood is even higher,” says Dr. Avari.