The Big O: Is this why you can't get there?

Sex doesn't always have to end in an orgasm. But it's nice when it does, and a lot of people equate good sex with the kind of reaction Meg Ryan's character had to her sandwich in "When Harry Met Sally."

In reality, putting orgasms on such a high pedestal is actually part of the reason why some women have such difficulty achieving them. “The vast majority of young, healthy women (no medical disorders, not related to a medication, they’re either single or in a healthy relationship) who come in to see me about never having an orgasm, it’s because of something mental," said Leah S. Millheiser, MD, director of the Female Sexual Medicine Program at Stanford University Medical Center. "Often times these women are aware that they are stopping themselves from reaching orgasm."

In this case, the inability to orgasm is a result of some anxiety surrounding letting go of control or the pressure society has put on "finishing," but there are also some underlying health issues Millheiser suggests ruling out.

Because blood flow and muscle contraction determine the intensity of a woman's orgasm, a peripheral vascular disease — a condition which reduces blood flow to the limbs — could be causing weak or nonexistent orgasms. "If someone has longstanding peripheral vascular disease, meaning they have blocks in their peripheral vessels (the blood vessels that go to their legs and their genitals) because of diabetes or high cholesterol, they have decreased blood flow. And when you have decreased blood flow to the genitals, your orgasms aren’t going to be anywhere near as intense."

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Multiple sclerosis, epilepsy, and other nervous system disorders can also impact orgasms, because they require have healthy neurological function in the genital region. Millheiser explained, "When the genitals are being stimulated, an orgasm requires a message going through the spinal cord to the brain."

Going through certain hormonal changes also can affect your ability to get there. Testosterone and estrogen levels fluctuate because of breastfeeding, birth control, and menopause, which Millheiser said can slow down nerve sensation through the clitoral region and make it difficult to orgasm. "One of the most common things women experience when they’re going through menopause is either it takes a really long time to achieve one — sometimes women can’t achieve one at all — and if they do have an orgasm, they feel like it’s a really small percentage of the intensity it used to be," Millheiser said.

Depression and other mental health issues can also interfere with a woman's ability to orgasm because of their impact on sexual desire, and the medications used to treat them don't help. In fact, SSRIs and SNRIs can make orgasming even harder because they stimulate certain serotonin receptors that cause a decrease in dopamine and norepinephrine in an area of the brain.

If these issues don't apply to you, your inability to orgasm could very well be caused by something as simple as your mental state. For example, if you’re stressed out or not that into the person you're having sex with, you're probably going to have a very hard time enjoying sex enough to climax.

It's always a good idea to talk to your doctor if you're concerned about your orgasm.