For couples facing infertility, understanding why they’re struggling to get pregnant can feel frustrating and overwhelming. Often the quality of sperm or the egg contribute to infertility, but in some cases the uterus can be the culprit.
“In terms of uterine factor infertility, it can be something related to … uterine shapes,” Dr. Rachel Beverley, a graduate medical fellow in reproductive endocrinology and infertility at UPMC Magee Womens Hospital, told TODAY. “Another issue with the uterus is whether or not it is receptive for implantation. So if there is other pathology within the cavity of the uterus.”
Understanding the uterus and the role it plays in fertility and pregnancy can be confusing and for many people, uterine shape or condition might not even play a role.
“Uterine (factor) infertility is probably one of the smaller percentages of infertility,” Dr. Anate Brauer, the IVF director at Shady Grove Fertility, New York, told TODAY. “About 30 to 40% will be unexplained infertility. And that’s a tough thing to tease out because you can be in the unexplained category but have an underlying uterine issue that you don’t know about.”
The experts share what people should understand about uteruses, fertility and pregnancy.
Uterus anomalies and fertility
Sometimes a uterus forms abnormally. Some anatomical shapes might contribute to infertility while others might make it tougher to carry a baby to term.
“In terms of the different shapes of the uterus, these are things women and young girls are born with because the uterus is developing in utero,” Beverley said. “The shapes of the uterus can be associated either with difficulty with conception or more commonly even with other complications once a woman is pregnant.”
Having a uterine septum, a type of barrier in the uterus, can contribute to recurrent miscarriages, for example.
“The outside of the uterus appears normal but the inside of the cavity of the uterus is basically divided by a wall of tissue, which is called the septum,” Beverley said. “That wall can extend either completely down the entire cavity of the uterus or just partially.”
This contributes to early miscarriage because the uterus isn’t receiving what it needs to support an embryo.
“A septum usually doesn’t have a blood supply in that wall in between and so an embryo tries to implant and it can’t implant on the septum because there’s not a good blood supply,” Brauer said. “So you have an early loss.”
For patients with recurrent miscarriages, doctors often preform an exam called a hysteroscopy to see the inside of the uterus. If there is a septum, doctors can remove it during that procedure, which can help women carry babies to term.
When someone has two separate uteruses it’s call uterine didelphys. While this sounds complicated, it doesn’t always lead to fertility problems.
“Someone with a didelphys shouldn’t have an issue carrying pregnancy to term as long as the uterus that they get pregnant is a normal size,” Brauer said.
Another common anomaly is a bicornuate uterus, where a person has half a uterus. It’s also referred to as a heart-shaped uterus. Again, the size of the uterus determines how well one can carry a baby.
“They don’t have so much infertility but they can have a higher risk of preterm delivery or breech (babies),” Brauer said. “Their uterus just doesn’t have enough space in there.”
Still others are born without a uterus. While uncommon, there’s little doctors can do to help them carry babies themselves and they often rely on surrogates. Some medical centers have performed uterine transplants, but they are rare and still experimental.
“This is new and not a standard of care at this time,” Beverley said.
Uterine conditions that contribute to infertility
While shape can play a role in fertility and pregnancy, conditions that impact the uterus can also make it tough to become pregnant.
“There’s obvious uterine factor infertility, such as Asherman’s syndrome, which is the scarring of the cavity,” Brauer said. “There’s more insidious underlying issues that could be uterine, like the inflammation in the uterus or adenomyosis.”
Scarring can occur after a dilation and curettage, other surgical or medical procedures on the uterus and sexually transmitted infections. Adenomyosis occurs when the endometrial cells nestle into the uterus’ muscle, which can sometimes form a mass or a cyst. Uterine fibroids, non-cancerous growths, can also make getting pregnant harder.
“We do know that those inside of the cavity of the uterus might lead to problems with getting pregnant,” Beverley said. “If we do find those within the cavity of the uterus of infertile patients generally, we like to remove those to optimize their success in the fertility treatments we give.”
Again, a hysteroscopy might help doctors see the inside of the uterus and treat the underlying condition by removing a fibroid or scarring, for example. But like other causes of infertility, there are some cases where treatment doesn’t work as hoped.
“Sometimes removal of a simple polyp or fibroid, yes that’s very easily treatable. Sometimes the scar tissue can be quite extensive and even if we remove it, it can still be problematic for the women to conceive,” Beverley said. “I wish that everybody had a clear cut, best way to go.”