How Women Can Be Pregnant Without Knowing It

And no, they're not just "crazy."
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On a July Tuesday two years ago, Michelle Mulvehill was visiting a friend who mentioned that she looked tired. Mulvehill agreed that she had not been feeling well, but chalked it up to a recent change in the weather and laughed when her friend wondered if she could be pregnant. Mulvehill, who was 35 at the time, had Polycystic Ovary Syndrome and hadn’t had her period in two years. She had also been diagnosed with infertility. Earlier in her life, Mulvehill had spent six years trying to get pregnant with her now ex-husband, seeing specialists and taking the ovulation-inducing drug Clomid -- with no success.

But Mulvehill couldn’t shake her friend's comment, so the next day she took a pregnancy test and was shocked to watch it turn positive. She took another. It was positive again. Mulvehill went to a doctor who confirmed that -- against the odds -- she was indeed going to have a baby, although he could not tell exactly how far along she was.

Then late the following Monday, Mulvehill began having stomach pains. At first, she thought it was simply gas, then -- as the pains continued through the night -- signs of a miscarriage. The next morning, she drove to the hospital where the staff gave her an entirely different assessment: They were contractions, Mulvehill was in labor, and she was already two centimeters dilated.

At 8:45 p.m. on Tuesday, July 16, 2013, Mulvehill delivered a baby girl via Cesarean section, just six days after discovering she was pregnant. Her daughter Lily was 3 pounds, 14 ounces. Mulvehill, her doctors reasoned, had been pregnant for 32 weeks without knowing it.

Michelle Mulvehill

Stories like Mulvehill’s are a source of fascination when they emerge in the media, and they do so with surprising frequency. In the last year alone, there was the woman who didn’t know she was 37 weeks pregnant until she gave birth on a plane (“Something fell out of me!” she shrieked to her boyfriend); the anonymous woman who spoke to Cosmopolitan about not knowing she was pregnant until she had just two months to go ("When I was told I was pregnant, I leant over into a sink and vomited for 30 minutes straight"); and the woman who went to the hospital to seek treatment for back pain, but instead ended up delivering a 10 pound, 2 ounce baby girl.

As these accounts circulate, there is that inevitable question, posed by incredulous readers in the comments section and exclaimed aloud: How can you possibly be pregnant -- in some cases, very pregnant -- and not know?

“Cryptic pregnancy” is the term sometimes used for cases where a woman doesn’t discover her pregnancy until she is at least 20 weeks, or roughly five months, along.

“What I’ve seen put out there in the literature is that [it happens in] roughly 1 in 500 pregnancies,” Dr. Kristin Sharp, an OB-GYN with the University of Wisconsin School of Medicine and Public Health told The Huffington Post. “I personally have seen more than 500 pregnancies, and I’ve probably seen one or two of these unexpected [pregnancies].”

There are many, seemingly quite rational, explanations for the phenomenon.

Women may get false negatives on pregnancy tests, for any number of reasons -- they test too early, don’t follow directions closely or use diluted urine. They may have spotting, which can occur throughout pregnancy, that they mistake for menstruation. Many women have highly irregular periods or no periods at all.

“There are a lot of medical conditions and medications that can prevent women from having periods,” Sharp said. When those women don't menstruate for months, they do not necessarily assume something is amiss. Physically, some women simply do not show much while they are pregnant, and though heavier women are perhaps more predisposed to that, Sharp added that she has personally been surprised by thin patients who barely look pregnant despite being relatively far along.

For her part, Mulvehill was accustomed to not getting a monthly period, because of her PCOS. She was also overweight at the time of her pregnancy and carrying her daughter low, so her stomach did not “stick out” any more or less than was normal for her, she said. In fact, Mulvehill was on a low-carb diet at the time and had lost a few pounds. Even the doctor who confirmed her pregnancy told her he did not feel a typical, hard “pregnancy bump.” She felt internal taps and tickles that she initially interpreted as gas bubbles, but now realizes were her daughter’s first movements -- a mixup that is not entirely uncommon.

“What I faced when my story came out was a lot of disbelief,” said Mulvehill, whose birth experience was featured on a Discovery show called "Outrageous Births: Tales From The Crib."

“People said, ‘You must not take good care of yourself if you didn’t know you were pregnant.' But that’s not true. I had been diagnosed with infertility. I had no nausea, no weight gain, my feet didn’t swell," she continued. "There was just no reason for me to think it was true.”

Michelle Mulvehill

Dr. Ruta Nonacs, a psychiatrist with the perinatal and reproductive psychiatry clinical research program at Massachusetts General Hospital, told The Huffington Post that some women may not recognize a pregnancy because of more serious mental health issues -- for example, a woman may have a psychotic disorder that does not allow her to correctly interpret her symptoms, or may have an extreme disassociation from her body stemming from some kind of sexual trauma.

But there are also many women who are absolutely “normal” psychologically, Nonacs said. “They’re probably just people who had irregular cycles, so they weren’t aware of their signs and symptoms, or [women] who didn’t think they could get pregnant at all,” she said.

“[Pregnancy] is a highly-charged thing, and highly-charged things are more likely to be minimized or accentuated,” she added. “We definitely see patients who come in with a huge, cancerous lump that’s so advanced we think, ‘Why didn’t you come in two years earlier?!'" But sometimes people simply "cannot see clearly" around issues that are as weighty as death and pregnancy, she said.

Caitlin Coakley Beckner, 28, can list plenty of reasons why it took her six months to recognize she was carrying a child. She had an intrauterine device (IUD), which has one of the highest efficacy rates of any form of birth control, and which generally kept her period-free. She was tired, but she had just started a demanding new job and was planning her upcoming wedding. Plus she was thin, and had actually lost weight during her first trimester as she prepared to walk down the aisle. And when she later started gaining weight, she thought it was simply because the wedding was over and she was being less diligent about her diet and going to the gym.

“I look at pictures and in retrospect, yes, it looks like a baby bump, but at the time I thought, ‘I need to go back on a diet,’” Coakley Beckner laughed. “I remember saying, ‘It’s weird, because when I poke my belly it feels hard underneath’… but it still didn’t add up to a pregnancy. There was nothing I was feeling that couldn’t be explained away.”

“That’s what people always want to know -- ‘how can you not know?’” continued Coakley Beckner, who wrote about her experience for XOJane. “I’m not sure it was denial; it just never even entered into my mind as a possibility to tell you the truth. I had mentally checked pregnancy off my list when I got my IUD.”

When she did realize she was pregnant, Coakley Beckner was flooded with worry about her baby's wellbeing. She had been drinking alcohol and eating foods that are often forbidden for pregnant women, but her OB-GYN reassured her that everything would likely be fine, and her son -- who is now 3 -- is extremely healthy and bright. As a self-described type-A planner, the shocking change in course caused her enormous stress. She and her husband both had intense jobs and had to quickly figure out how they would balance their careers with unexpected parenthood. They were living in a small one-bedroom apartment, and had relatively little time to prepare.

Caitlin Coakley Beckner

“I got really bad postpartum depression,” Coakley Beckner said. “Every parent has that moment when their baby is crying and they can’t figure out why. But for me, the fact that I hadn’t known I was pregnant for so long had me thinking that maybe there was just some maternal instinct I’m missing,” she said. “It fed my self-doubt.”

No studies have looked at the emotional outcomes associated with cryptic pregnancies, but Nonacs said it's fair to draw hypotheses from research exploring mental health outcomes associated with unplanned pregnancy in general. Many of those studies have found unplanned pregnancy can absolutely be a risk factor for subsequent anxiety and depression, she said.

“It’s a significant transition in one’s life, which might be met with positively, or might create a lot of stress. How women view the situation, and how much support they get, may have a huge bearing on how well they do during their pregnancy and postpartum," Nonacs explained. "I would think, purely anecdotally, that [women who are surprised by a pregnancy] are probably at higher risk for psychological distress.”

Three-and-a-half years after the birth of her first son, Coakley Beckner gave birth to another boy, who was just one week old when she spoke to The Huffington Post. Emotionally, she said, her second pregnancy was completely different. Planning to get pregnant, and having time to prepare herself once she was meant that she was calmer about the whole ordeal, and more attuned to the changes happening in her body.

But that does not mean her second pregnancy was necessarily better, she said, nor is she at all embarrassed by the story of how her first baby came into the world.

“When I hear stories about women who didn’t know, and I read comments from people who just seem so appalled, I want to jump in and say, ‘This can happen!’” she said. “And I’m not crazy.”

Also on HuffPost:

1. Your Blood Volume Increases

7 Awesome Things Your Body Does During Pregnancy

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