What?! Study results are often surprising and random and this one is no different. After a double embryo transfer, women who are 5’7” or taller are twice as likely to carry twins as are shorter women. Data from a Dutch study of almost 20,000 women who underwent IVF was dwindled down to 2,357 who had a first fresh double embryo transfer (not frozen) and looked at factors that may be important to outcome including weight, height, age, number of retrieved eggs, alcohol use, education, etc.
Only two factors were found to be significantly associated with twinning: women taller than 5’7" were twice as likely to have twins as were shorter women, and women who had more than 11 eggs retrieved were 2.4 times more likely to have twins.
The association between increased height and pregnancy is difficult to explain. One of the authors proposed the idea that taller women have increased VEG-F levels (vascular endothelial growth factor) and growth hormone which may make them more prone to conceive twins.
Why is this important? Well, infertility docs are faced with a constant balancing act between giving the best chance of achieving a pregnancy without incurring the problems associated with multiple births. This information could possibly be used to assist in the choice between single and double embryo transfer. Multiple pregnancies involved a higher risk of problems for the mother, such as preeclampsia, and also for the baby because of preterm or immature delivery. So, other than just being a thought provoking finding, it may help us down the line.
- Dr O.