WOMEN aged 25 to 29 are helping to nudge up the rate of multiple births, figures suggest.

New data from the Office for National Statistics (ONS) shows the rate of multiple births, mostly of twins, rose to 16.1 per 1,000 women giving birth in 2015, compared with 16.0 in 2014.

In 2015, 10,901 women gave birth to twins, 169 to triplets and three to quads and above. Most twins and triplets are conceived naturally, but fertility treatment also increases the chance of a multiple birth. On average, one in 10 IVF pregnancies results in a multiple birth.

In the past, women aged 45 and over drove the rise in multiple births, due to higher levels of IVF among this age group. But, in 2015, the rise was fuelled by women aged 25 to 29.