That children are "born too small for the time being" means that they are born with a birth weight below the expected.

Among men who sought care for infertility, care needed to carry out ICSI for 63 percent of men born small at the time, but only for 45 percent of men born normal weight.

It shows a dissertation by Susanne Liffner, who is chief physician at the gynecology clinic at the University Hospital in Linköping and doctor at Linköping University.

- I think that this can mostly be used as an explanation for some men who have difficulty becoming fathers.

What we have also seen is that it goes just as well when you do a test tube fertilization as it would have if you had been born a normal size, says Susanne Liffner.

Often small for the time being

Another study examined men born between 1973 and 1986 who had been patients at the Reproductive Medicine Center in Linköping due to infertility.

The results then showed that men who had a male explanation for infertility were more likely to be born small before pregnancy, or had a low birth weight compared with men who did not have children due to factors in the woman or where the infertility was unexplained.

- There are not many who are born small at the moment.

It is really about a few percent of all children, says Susanne Liffner.

In the clip above, Susanne Liffner explains more about what she came up with.

You can read the entire study here.