WOMEN WHO EAT less fruit and more fast food take longer to get pregnant and are less likely to conceive within a year, a new study published in the Human Reproduction journal has found.

During their first antenatal visit, research midwives in Ireland, the UK, Australia and New Zealand asked 5,598 women about their diet. The women had not had a baby before.

Compared to women who ate fruit three or more times a day in the month before conception, women who ate fruit less than one to three times a month took half a month longer to become pregnant.

Similarly, compared to women who never or rarely ate fast food, women who consumed fast food four or more times a week took nearly a month longer to become pregnant.

Among all the couples in the study, 468 (8%) couples were classified as infertile (defined as taking longer than a year to conceive) and 2,204 (39%) conceived within a month.

When the researchers looked at the impact of diet on infertility, they found that in women with the lowest intake of fruit, the risk of infertility increased from 8% to 12%, and in those who ate fast food four or more times a week, the risk of infertility increased from 8% to 16%.

“These findings show that eating a good quality diet that includes fruit and minimising fast food consumption improves fertility and reduces the time it takes to get pregnant,” Professor Claire Roberts, Llyod Cox Professorial Research Fellow at the University of Adelaide, who led the study, said.

First author, Dr Jessica Grieger, post-doctoral research fellow at University of Adelaide, added: “We recommend that women who want to become pregnant should align their dietary intakes towards national dietary recommendations for pregnancy. Our data shows that frequent consumption of fast foods delays time to pregnancy.”

The study

During the first antenatal visit at around 14-16 weeks’ gestation, midwives collected information about the time it took to become pregnant and the women’s diet. This included details of their diet in the month before conception, and how frequently they consumed fruit, green leafy vegetables, fish and fast foods.

Couples were excluded from the analysis if they were receiving fertility treatment due to the male partner’s infertility.

“Most women did not have a history of infertility. We adjusted the relationships with pre-pregnancy diet to take account of several factors known to increase the risk of infertility, including elevated body mass index (BMI) and maternal age, smoking and alcohol intake,” Dr Grieger said.

“As diet is a modifiable factor, our findings underscore the importance of considering preconception diet to support timely conception for women planning pregnancy,” she said.

The researchers also found that while intake of fruit and fast foods affected time to pregnancy, pre-pregnancy intake of green leafy vegetables or fish did not.

Limitations of the study include the fact that collecting data on pre-pregnancy diet relied on retrospective recall and included a limited range of foods. Information on the fathers’ diet was not collected, and it is possible that other, unknown factors might have affected the results. A major strength is the large group of women included in the study.

“For any dietary intake assessment, one needs to use some caution regarding whether participant recall is an accurate reflection of dietary intake,” Dr Grieger said.

“However, given that many women do not change their diet from pre-pregnancy to during pregnancy, we believe that the women’s recall of their diet one month prior to pregnancy is likely to be reasonably accurate,” she said.

The researchers are continuing their work and plan to identify particular dietary patterns, rather than individual food groups, that may be associated with how long it takes women to become pregnant.