Naturally conceived twins occur once in around every eighty nine births. The majority of twins who are born are non identical and a result of two eggs being fertilised. Some fraternal twins look very similar; others share some resemblance whilst the remainder may not even look the slightest bit related.
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.
It is estimated that 1 in 250 natural pregnancies will naturally result in twins.
What are the signs of a twin pregnancy? The signs of a twin pregnancy are different for everyone, but typically include heightened normal pregnancy symptoms. Common signs include more severe nausea Opens a new window, earlier weight gain, intense fatigue and increased appetite.
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.
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.
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.
The birth process is similar to giving birth to a single baby. If you're planning a vaginal birth, your health team may recommend that you have an epidural for pain relief.
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.
You Can Only Control the Things Within Your Control
“Having twins is not twice as hard—it's exponentially more difficult,” says Natalie Diaz, author of What To Do When You're Having Two and CEO of Twiniversity, a global support network for parents of twins.
The biological phenomenon of giving birth to twins with two different biological fathers is called heteropaternal superfecundation. This happens when a second ova released during the menstrual cycle is fertilised by sperm cells of a different man from separate sexual intercourse.
Don t be surprised if you develop a bit of a 6 weeks pregnant belly. Although your 6 week embryo is still well down in your pelvis, some women, especially those who've been pregnant before, seem to show much earlier. General abdominal distention is usually the cause.
A woman's peak reproductive years are between the late teens and late 20s. By age 30, fertility (the ability to get pregnant) starts to decline. This decline happens faster once you reach your mid-30s. By 45, fertility has declined so much that getting pregnant naturally is unlikely.
Are twins hereditary? Yes, some types of twins are hereditary, meaning that twins run in families. Heredity on the mother's side ups a couple's odds of conceiving fraternal twins. Fraternal twins are two babies from two different eggs that were released from the ovaries simultaneously.
Rate of twin births in the U.S. in 2020 and 2021, by month
In 2021, the month with the highest rate of twin births in the United States was July with almost 33 twin births per 1,000 total births.
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).
As a parent of twins, I'm pretty sure that you know the answer to the question “which twin is older?” It is, of course, the child that was born first.
If more than one sperm fuses—a condition called polyspermy—multipolar or extra mitotic spindles are formed, resulting in faulty segregation of chromosomes during cell division; nondiploid cells are produced, and development usually stops.
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".
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.
When tracking pregnancy symptoms week by week, whether with one baby or twins, 5 to 8 weeks pregnant is when nausea and vomiting—aka morning sickness—might kick in. Though the precise cause or causes of this condition are unknown, the pregnancy hormone human chorionic gonadotropin (hCG) may be a contributing factor.
Assisted reproduction
Taking fertility medication is one of the most common ways to get pregnant with twins. They increase fertility by stimulating egg production. If more eggs are produced, the chances that more than one egg will be released during ovulation also increase.
Do Twins Skip a Generation? If your father was a twin but you weren't, are you more likely to have twins? 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.