multiple birth

(redirected from Multiple Births)
Also found in: Dictionary, Medical.
Related to Multiple Births: Octomom, Septuplets

multiple birth,

bringing forth of more than one offspring at birth. Although many smaller mammals bear several young at a time, multiple births are relatively uncommon in humans and other primates. Twinning, the process that leads to the production of more than one offspring, results in twins, and with decreasing frequency, triplets, quadruplets, quintuplets, sextuplets, septuplets, and octuplets.

In the one-egg, or identical, type of twinning, a single fertilized ovum divides to form two complete organisms. Such twins are always of the same sex, are usually extraordinarily similar in physical appearance, and have identical blood-group types. Twinning to form one-egg identical twins usually takes place early in pregnancy. If considerable development has taken place before the twinning occurs, there may be an incomplete separation of the two embryos resulting in conjoined twinsconjoined twins,
congenitally united organisms that are complete or nearly complete individuals, historically known as Siamese twins. They develop from a single fertilized ovum that has divided imperfectly; complete division would produce identical twins, having the same sex and
..... Click the link for more information.
. Despite their similarities, identical twins have epigenetic differences that influence how their common DNA is used and expressed.

Fraternal twins, which are more common than identical twins, are those that develop from two separate ova, each fertilized by a sperm. Fraternal twins may or may not be of the same sex and need not resemble each other more than do any other two offspring of the same parents. In the United States twins occur once in approximately 40 births. In rare cases, non-identical embryos can fuse in the womb to produce a condition called chimerism, in which some of the individual's cells come from one of the embryos and the rest of the cells come from the other, genetically distinct embryo.

The incidence of multiple-egg births is in part genetically determined, varying according to race and family tendencies; and it is also influenced by external factors, i.e., the incidence increases with increasing age of the mother and the number of children she has already borne. One-egg, or identical, twinning occurs with the same frequency in all women, regardless of race, age, or other factors. There is evidence from comparative biology that deleterious factors in the environment of the newly fertilized ovum, such as a reduction in oxygen, increase the likelihood of one-egg twinning. Fertility drugsfertility drug,
any of a variety of substances used to increase the possibility of conception and successful pregnancy. Different methods are used to correct or circumvent the many different functional disorders of both males and females that can interfere with conception and
..... Click the link for more information.
 such as clomiphene, which are used when the cause of infertility is lack of released ova, sometimes cause several ova to be released and fertilized simultaneously. The use of these drugs has led to a rise in the incidence of multiple births, including sextuplets, septuplets, and octuplets.

References in periodicals archive ?
Multiple births caused by fertility treatment are draining millions of pounds from the NHS, an expert said yesterday.
Most doctors now only insert two or three eggs to avoid such multiple births.
The most recent Irish Maternity Indicator System report for 2015 said six hospitals have recorded multiple births above the national average - with assisted reproduction linked to the increase in five of the hospitals.
The new ONS figures also show 10,951 mothers had a multiple birth in 2016 - but this data includes both live births and still births.
Twins and Multiple Births Association's Chief Exec Keith Reed said: "The fact they are meeting all their developmental milestones is wonderful news.
Multiple births can also be due to genetic reasons, explains Dr Naeema Utman, a gynaecologist at HMCP.
The report, from the Office for National Statistics (ONS), said: "Although most multiple births occur naturally, many occur as a result of fertility treatment.
Paul and Tracey |face up the reality of multiple births
Neri Colmenares and Carlos Isagani Zarate who both noted that children of multiple births, aside from needing extra care and attention, also bring added financial expenses for the parents.
The number of multiple births from assisted reproductive technology continues to decline, with no more than 1% of women undergoing the procedures delivering triplets or higher orders of multiples in 2011.
The project was entitled Meeting the Health and Social Care Needs of Families with Multiple Births and aimed to explore the lived experiences of families, including the impact of multiple births upon partners and children, and sources of support.

Full browser ?