Highest number of twins ever with boom in births
The world may have reached "peak twin" with more sets of twins being born than ever before, according to new research.
A study found there is currently the highest number of twins in the world on record, but that the figure is levelling out in most countries.
An increase in delayed childbearing techniques and treatments such as IVF are the main reasons for the twin birth boom, according to Oxford University researchers.
Lower fertility, more people starting families later in life, and an increase in contraception use also played a part in the twin birth boom, data showed. The study, led by Dr Prof Christiaan Monden, found that techniques such as IVF, ICSI, artificial insemination and ovarian stimulation all increase the chance of giving birth to twins. This is because the hormones in these treatments that stimulate egg production can lead to women releasing two eggs at once. Each year, 1.6m twins are born and 12 per 1000 births worldwide are twins.
This is a rise of a third from the 1980s, when the twin birth rate was 9 per 1000.
Prof Monden said the rates are higher than they have been for 50 years.
The increase has mainly been in non-identical twins, who develop from separate eggs and sperm.
Identical twins - who are born from an embryo splitting in half after fertilisation - are being born at around the same rate as before. Prof Monden’s team analysed twin birth rate data from 165 countries from 2010 to 2015, then compared this with data from 1980 to 1985. Giving birth to twins is riskier for mothers and children.
Prof Monden says twin births are associated with "higher death rates among babies and children, and more complications for mothers and children during pregnancy, and during and after delivery".
In Sub-Saharan Africa, more than 200,000 twins lose their co-twins within a year. It comes as new research suggests the pandemic has led to a fall in birth rates in developed countries.
In France, there were 13% fewer births in January 2021 compared to January 2020, according to France’s statistics institute.
France has traditionally had the highest fertility rate in the EU, but statisticians say this is the biggest fall in births since the 1970s when the baby boom ended. The UK and US have experienced a similar drop in births since the pandemic took hold.
The number of births often falls in developed countries during pandemics and economic crises, with potential parents anxious about job security and financial troubles.