Fertility treatment Some fertility drugs work by stimulating a woman's ovaries, which can sometimes cause them to release more than one egg. If sperm fertilizes both of these eggs, this can result in twins. In vitro fertilization (IVF) can also increase the chance of conceiving twins.
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.
Multiple pregnancy usually happens when more than one egg is fertilized. It also can happen when one egg is fertilized and then splits into 2 or more embryos that grow into 2 or more babies. When one fertilized egg splits into 2, the babies are called identical twins.
Foods naturally rich in folic acid like avocado, spinach, broccoli, liver, and legumes also have the tendency to increase one's chances of conceiving twins. According to a study, consuming extra folic acid while trying to get pregnant can raise the chance of giving birth to twins slightly higher.
Although certain factors increase the chance of having twins, there is no way to improve the odds of having twins naturally. A woman will usually find out that she is pregnant with twins from an ultrasound early on in the pregnancy.
Monozygotic (MZ) twins, also called identical twins, occur when a single egg cell is fertilized by a single sperm cell. The resulting zygote splits into two very early in development, leading to the formation of two separate embryos.
For a given pregnancy, the odds of conceiving fraternal twins are only determined by the mother's genetics, not the father's.
The quick answer to this question is that, in a twin pregnancy, it is the mother's genes that determine twins. First up, giving birth to identical twins is not genetic, but conceiving fraternal twins is. The mother may have the genetic trait of releasing two eggs in one menstrual cycle.
Everyone has the same chance of having identical twins: about 1 in 250. Identical twins do not run in families. But there are some factors that make having non-identical twins more likely: non-identical twins are more common in some ethnic groups, with the highest rate among Nigerians and the lowest among Japanese.
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.
To form identical or monozygotic twins, one fertilised egg (ovum) splits and develops into two babies with exactly the same genetic information. To form fraternal or dizygotic twins, two eggs (ova) are fertilised by two sperm and produce two genetically unique children.
If one egg is fertilised by two sperm, it results in three sets of chromosomes, rather than the standard two - one from the mother and two from the father. And, according to researchers, three sets of chromosomes are "typically incompatible with life and embryos do not usually survive".
37 men who had fathered non-identical twins with a control group of 349 men with normal, healthy sperm. On average, they found that fathers of twins had more normal and motile, or mobile, sperm than the control group. Their sperm counts were also higher, although not significantly.
A man with a family history of twins may carry the gene, but it won't mean he can father a set of non-identical twins. The gene is only expressed through women who ovulate. If he has daughters, they may inherit the gene, and one day go on to have fraternal twins.
Human eggs use chemical signals to attract sperm. New research from Stockholm University, Manchester University NHS Foundation Trust and The University of Manchester shows that eggs use these chemical signals to “choose” sperm. Different women's eggs attract different men's sperm – and not necessarily their partners..
If the egg fertilized the couple were more likely to conceive a baby boy. Female sperm were found to be slower, fitter and would live longer than male sperm so making love earlier in the fertile window meant they would still be alive to fertilize the egg, and more likely to conceive a baby girl.
Superfecundation is the fertilization of two or more ova from the same cycle by sperm from separate acts of sexual intercourse, which can lead to twin babies from two separate biological fathers. The term superfecundation is derived from fecund, meaning the ability to produce offspring.
There are two ways that a woman may conceive twins. In one case, her ovaries release two eggs at the time of ovulation, and both are fertilized and become embryos; this results in fraternal, or nonidentical, twins. In contrast, identical twins are conceived when one embryo splits into two early in its development.
Sometimes a woman's ovaries release 2 eggs, and a separate sperm fertilises each egg. This forms twins. These twins are called fraternal twins, dizygotic twins (meaning two zygotes) or non-identical twins.
#1 Fraternal twins can be conceived as much as 24 days apart
For this reason, fraternal twins can be conceived a few weeks apart, though they generally will be born at the same time.
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). Remember that sex and gender are not the same.
A little more than half of twin pregnancies end in preterm delivery (before 37 weeks). 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).
Women with twin pregnancies are more likely to have pregnancy health problems and complications like gestational diabetes, pre-eclampsia, premature labour and bleeding. Twins who share a placenta might have extra complications.
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.
Ultrasound. Although the factors above may be signs of a twin pregnancy, the only sure way to know you're pregnant with more than one baby is through an ultrasound. Some doctors schedule an early ultrasound, around 6 to 10 weeks, to confirm the pregnancy or check for issues.