The female orgasm is infuriatingly finicky: Almost half of women have frequent trouble getting off, a new study from Valparaiso University suggests.

Researchers surveyed 866 women about their sex lives, and 48 percent of them said they had difficulty climaxing during at least half of their sexual encounters.

The researchers asked those women follow-up questions to see if there were any commonalities that could explain their troubles. They identified three factors that seem to be linked to orgasm difficulty.

Read on for what you can do about it.

Her Age Could Explain Why She’s Not Climaxing

Younger women seem to have more trouble getting off: 40 percent of those in their twenties reported problems reaching orgasm, compared to only 30 percent of women age 30 or over.

That’s because younger women tend to have less experience in the bedroom, says lead study author David Rowland, Ph.D. It can take a woman years to discover what sends her over the edge, and when she’s young, she simply hasn’t had as much practice.

Younger women also tend to be in newer relationships—other research suggests that women are more likely to orgasm with long-term partners. Plus, they might be reluctant to tell you what they want in bed, says Rowland.

Your solution: Speak up. Ask her if what you’re doing feels good, Rowland suggests, and tell her when she does something that feels amazing to you. Open lines of communication will help you both figure out what works for her.

A Lack Of Arousal Could Be Killing Her Orgasm

Nearly half of the women who found it difficult to climax said they also had trouble becoming psychologically aroused.

Reaching orgasm isn’t just about pressing the right buttons physically, says Rowland. The mental component is also crucial for many women: They have to feel turned on in order to get off.

This psychological arousal boils down to how intimate the situation feels and how  connected she feels to you, he explains.

For ideas on how to light her fire, check out these 33 Ways to Turn a Woman On.

She Might Need More Lube to Get Off

It’s also possible that a woman is mentally turned on, but has trouble getting wet, says Rowland.

In the study, 43 percent of the women who had issues reaching orgasm also had a hard time getting and staying lubricated. That lubrication makes sex feel more comfortable and pleasurable for her—so when it’s missing, so is her orgasm.

The fix is easy: Get your lube from a tube. Nearly half of women who’ve used lube say it makes it easier for them to come, according to Indiana University research.

Here’s The Complete Guide to Choosing the Best Lube For You.