Understanding the Difference between Identical and Fraternal Twins

Multiple births are more common than in the past, owing to the increasing average age of women and the accompanying increase in assisted reproductive techniques, most notably the use of fertility medicines. Twins account for more than 90% of all multiple births. Twins are classified as identical (monozygotic) or fraternal (dizygotic).

To produce identical twins, a fertilised egg (ovum) divides and produces two newborns with identical genetic material. This is in contrast to fraternal twins, who are produced when two eggs (ova) are fertilised by two sperm, resulting in two genetically distinct children who are no more identical than individual siblings born at different dates. Twins have about equal chances of being female or male. Contrary to popular perception, twins do not occur in successive generations.

Factors that enhance the likelihood of having twins: 

Certain women are more likely to give birth to twins than others. Several factors contribute to the likelihood of success, including the following:

Mother’s age increases – women in their 30s and 40s have higher estrogen levels than younger women, which stimulates their ovaries to create more than one egg at a time.

Previous pregnancies – The more pregnancies a woman has, the greater her chance of conceiving twins.

Heredity – if a woman is a fraternal twin, has already had fraternal twins, or has fraternal twin siblings, she is more likely to conceive fraternal twins.

Race – Twins are more common in black African women than in Asian women.

Assisted reproductive treatments – a variety of procedures stimulate the ovaries with fertility medicines to generate eggs, which are frequently discharged in multiples per ovulation.

Fertilisation:

The menstrual cycle is regulated by hormones generated by the ovaries and a tiny gland in the brain called the pituitary. The usual cycle lasts approximately 28 days. Following menstruation, growing levels of the hormone oestrogen assist in thickening the uterine lining (the endometrium) and releasing an egg from one of the ovaries (ovulation).

If the egg is fertilised during its descent through the fallopian tube, it becomes lodged in the thicker uterine lining, begins dividing, and develops into an embryo.

Twins who are identical or monozygotic: 

Around one in every three sets of twins are identical. This occurs when the fertilised egg divides in half while remaining a minuscule collection of cells. The self-contained halves then develop into two identical newborns.

Twins born from a single egg and sperm are referred to as identical or monozygotic’ (one-cell) twins. The biochemical mechanisms through which a single fertilised egg divides into two remain unknown.

Approximately one-quarter of identical twins are mirror images of one another, which implies that one child’s right side mirrors their twin’s left side.

The causes of Identical Twinning:

 In most cases, the causes of monozygotic twinning are unknown. Nobody truly comprehends why an egg divides. Technically speaking, it is a breakdown in the regular development process.

There is no inherited factor that increases your likelihood of having identical twins. Identical twins, on the other hand, do not run in families. While certain families have a high incidence of identical twins, this is just coincidental.

Twins who are fraternal or ‘dizygotic’:

Approximately two out of every three sets of twins are fraternal. When two distinct eggs (ova) are fertilised by two distinct sperm, fraternal or ‘dizygotic’ (two-cell) twins occur. These infants will bear no resemblance to siblings born at different dates. The babies can be identical or different sexes, with nearly equal probability for either.

Twin gestation:

A single baby’s gestation period is typically around 40 weeks. However, twins, whether identical or fraternal, typically gestate for approximately 38 weeks. This shorter time period is due to the greater demands on the mother’s body and the infants’ inability to acquire all of the nutrients they require while still in the womb.

Due to the fact that twins are typically born prematurely, they are more likely to have low birth weights. Prematurity increases the likelihood of developing a variety of illnesses, including jaundice.

Reduce Your Chances of Conceiving Twins:

Dizygotic twinning has increased in industrialised countries worldwide, owing in great part to fertility treatments. For several decades, twin rates increased steadily until around 2000, when they began to stabilise. 10

This is because as fertility treatment technology evolved, reproductive professionals discovered strategies to decrease the incidence of multiple pregnancies. The goal of infertility therapy should always be to deliver one healthy kid at a time, as this is the healthiest option for both the gestational parent and the fetus. While there is no way to totally remove the chance of twins during fertility therapy, there are a few choices.

Conclusion:

Twins account for more than 90% of multiple births.To produce identical or monozygotic twins, one fertilised egg (ovum) divides and develops into two identical newborns with identical genetic material.

Two eggs (ova) are fertilised by two sperm to generate two genetically distinct offspring known as fraternal or dizygotic twins.