How are quadruplets formed?
Conceived naturally, the quadruplets were born via C-section and consist of two girls, Bunono and Bungcwele, and two boys, Bubele and Buchule.
Mom and babies are doing well.
- Also see: Cape Town quadruplet mom lavished with baby shower
- Also see: How to cope with your multiple pregnancy
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A rare occurrence
Not much research has been done on how many multiple births have occurred in South Africa but globally, multiple births make up only 3% of all births.
Quadruplets are by far rarer than twins and triplets:
- In 2007, 3 500 sets of sets of quadruplets were born worldwide.
- In Canada, 1 in every 729 000 births are quadruplets.
- In the US, 217 quadruplet births were recorded in 2016.
“Though twins and higher order pregnancies are more common with assisted reproduction, spontaneous quadruplet conception is extremely rare – it is quoted to be between 1 in 512 000 to 1 in 677 000," explains Dr Malika Patel of the Department of Obstetrics & Gynaecology at the University of Cape Town.
She notes that complications during these pregnancies are more common than not. “There are 4 babies in the womb, space is limited therefore they are at risk of complications that occur more frequently than with singleton or twin pregnancies.
“Maternal complications include hypertension, gestational diabetes, and anaemia among others. There is an increased risk of miscarriage, preterm delivery, intrauterine growth restriction and delivery via caesarean section. In addition, the babies will require close monitoring for neonatal complications associated with early delivery of small babies.”
You may have a general idea of how conception takes place in a multiple pregnancy, with the example of twins the most commonly known.
In the case of twins, babies can be either:
- identical twins: where a single egg cell is fertilised by one sperm cell and splits to form two embryos; or
- fraternal: two separate egg cells are fertilised by two separate sperm cells and results in two embryos.
Identical twins are always the same gender and share the exact same DNA, whereas fraternal twins could be either gender and each will have their own unique genetic make-up.
With quadruplets, the process becomes a little more complicated, and the possibilities of having all boys, all girls, or a combination of both, as in the case of Inga Mafenuka's quadruplets, depends on a few factors.
“They can be either fraternal, resulting from fertilisation of 4 eggs with 4 sperm, or identical, resulting from a fertilisd egg that splits into 2 or more embryos, or a combination of these,” she says.
“In the case of fraternal quadruplets the babies can be of any sex, and they will not be identical. It would be like any other brother and sister. However, when they are all of the same sex or there are 2 boys and 2 girls, there is a chance that this could have been 2 sets of twins where the 2 girls are a set and the 2 boys are a set – that is you have 2 fertilised eggs that have each split into 2 embryos. Remember you can only have babies of the same sex when you have monozygotic twinning (twins developing from the same fertilised egg) because they have identical chromosomal make-up.”
The possibilities in spontaneous quadruplets are determined by whether:
- a single egg cell is fertilised by one sperm cell and splits into four identical embryos – this will result in four identical babies, same gender, same DNA.
- four separate egg cells are fertilised by four separate sperm cells and develop into four embryos – here the babies could be either gender and will not have the same exact DNA, but the four siblings are born at the same time.
- a single egg cell is fertilised by one sperm cell and splits into 3 identical embryos, while the fourth is a single egg cell fertilised by one sperm cell – this results in triplets of the same gender plus one sibling.
- a single egg cell is fertilised by one sperm cell and splits into two identical embryos twice over resulting in two sets of identical twins.
- two separate egg cells are fertilised by two separate sperm cells resulting in two separate embryos, along with a single egg cell fertilised by one sperm cell and splits into two identical embryos – here the combination is one set of fraternal twins and one set of identical twins.
We can't be 100% certain which combination the Mafenuka quadruplets could be though we know it won't be numbers one or three, but we wish Inga all the best on her new journey.
What is it like parenting multiples? Tell us by emailing to firstname.lastname@example.org and we could publish your letter.
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