A Dutch study presented Monday found taller women who become pregnant after receiving two embryos through in-vitro fertilisation have more chance of giving birth to twins.
According to Marieke Lambers of the VUMC, Gynaecology Obstetrics and Reproductive Medicine in Amsterdam and her team, it is the first time that a link has been found between the height of the mother and the probability of multiple births following IVF.
"This is a further step towards the development of tailor-made personalised IVF treatment," she said.
Her team studied 19,840 women from 1983 to 1995. Of those, 6,589 completed their first IVF cycle and 2,357 received two embryos, which resulted in 371 single births and 125 twin pregnancies.
"When we came to analyse the twin group, we found that a maternal height of over 1.74 m (five feet, nine and a half inches) and more than 11 oocytes [eggs] retrieved were independently associated with twin pregnancies," Lambers said.
"The positive relationship between a higher number of oocytes retrieved and a twin pregnancy probably reflects the fact that these women would have had a larger choice of good-quality embryos. But the association between increased height and multiple pregnancy is more difficult to explain," she said.
The work was presented Monday at the annual conference of the European Society of Human Reproduction and Embryology (ESHRE) in Stockholm.
Fertility clinics generally transfer several embryos to the uterus in the hope that one leads to a live birth. Multiple births are increasingly viewed as a problem by fertility specialists, who point to complications at birth and to problems in child development.