The study published today (Friday 4 May) in Human Reproduction, one of the world's leading reproductive medicine journals, asked 5598 women in Australia, New Zealand, the United Kingdom and Ireland about their diet.
New findings reported in Human Reproduction, suggest that getting pregnant takes longer for women who consume too much junk food and not enough fruit, as well as having a decreased chance of conceiving within a year.
The risk of infertility was also higher for women who ate very little fruit.
In total, 8 percent of the couples took 12 months to conceive, while 39 percent conceived in one month or less.
Similarly, consuming less fast food was associated with getting pregnant faster - but again, the difference in time between those eating the most junk food and those eating the least was tiny, between 0.4 and 0.9 months.
The majority of women in the study got pregnant within a couple of months of beginning to try, and the difference in time to conception between those consuming no fast food and those consuming the highest amount was actually only 2 to 4 weeks.
"A recent review on male diet and fertility markers indicated that higher intake of fruits and vegetables was associated with increased sperm motility whereas a higher intake of fat-rich foods and candies may decrease semen quality", the researchers wrote. They described how often they ate fast food, fish, leafy vegetables and fruit during that period. All of the women were in the first trimester of their first pregnancy. Frequency of eating fast food, fish, fruit and green vegetables was specifically assessed.
Midwives looking after these women were instructed to interview them about their diet in the month before they conceived and to record how long it took the women to get pregnant once they started trying.
The study took into account other factors which can increase the risk of infertility, such as body mass index (BMI), maternal age and smoking.
In this instance, fast food refers to burgers, pizza, chips, deep fried chicken, and anything you can get takeaway or at a fast food place. Grieger said, "For any dietary intake assessment, one needs to use some caution regarding whether participant recall is an accurate reflection of dietary intake".
Mathur further stated that the research is directly in line with other studies that "show your overall dietary pattern may influence fertility". "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".