什么是神秘怀孕，为什么会发生？

如果你现在怀孕了，或者曾经怀孕过，可能很难理解为什么有人可能不知道自己在怀孕。毕竟，怀孕有很多不同的症状，有些甚至在那两条粉红色的线出现之前就开始了（超级痛的胸部，有人吗？).但事实是，有一小部分人设法进展了几个月，却从未意识到有一个婴儿在路上——这种现象被称为隐性怀孕或秘密怀孕。

法尔研究所专注于医学研究的执业医学博士丹尼尔博耶(丹尼尔博耶)说，这种类型的怀孕是一种罕见的情况。但最近的科学研究显示，475次怀孕中有一次可以归类为隐性怀孕，这意味着怀孕至少要20周才能被发现。更罕见的是，大约2500人中有一人在分娩前不知道自己在怀孕。

RELATED:你的怀孕症状一周又一周以下是神秘怀孕是如何发生的，以及"我不知道我怀孕了"的常见原因。

How Does a Cryptic Pregnancy Happen?

一般来说，怀孕被定义为当某人怀孕20周或更长时间而不知道自己怀孕了。在这里，我们列出了一些因素，这些因素可能会使隐性怀孕更有可能发生。

Lack of Pregnancy Symptoms

通常，隐性怀孕的发生是因为这个人要么非常轻微，要么没有怀孕的症状。纽约市儿科住院医师、哥伦比亚大学儿科助理教授丽贝卡戴蒙德(丽贝卡戴蒙德)说，当女性出现这种妊娠状况时，她可能不会意识到自己怀孕了，因为没有典型的妊娠迹象，比如疲劳、恶心和呕吐、月经不调或腹痛

Mistaken Pregnancy Symptoms

当有人把自己的症状完全归咎于其他事情时，也可能发生隐性怀孕。例如，早孕疲劳可能被误认为睡眠不好或压力过大。呕吐、胃灼热和腹胀？消化问题！错过了例假？只是一个

other irregular cycle. "A pregnant person can continue to have bleeding that resembles menstrual periods, can have irregular bleeding, or can not have periods but not think of this as a sign they might be pregnant due to having underlying conditions that make their periods very irregular already," says Dr. Diamond.

Small Baby Bump

What about the unmistakable baby bump that usually appears in the middle of pregnancy? As it turns out, bumps aren't always super noticeable, which can make cryptic pregnancy more likely. "Depending on how the fetus is positioned in the womb, its growth rate, and body weight distributions, women experiencing cryptic pregnancies may not show prominent baby bumps," says Dr. Boyer. "This is especially common in younger women who are very athletic and are getting pregnant for the first time, because their abdominal muscles have never stretched before as a result of pregnancy, making them even tighter." Pregnancy bumps may also be hidden in overweight individuals.

• RELATED: 7 Reasons for a Late Period That Don't Mean You're Pregnant

No Positive Pregnancy Test

False negative pregnancy tests definitely aren't common, but they can happen, especially if the test was taken too early or improperly. This could certainly cause someone to have a false sense of assurance that they aren't pregnant when, in fact, they're actually expecting a baby. "The hormone that is positive in a pregnancy test (hCG) is also the hormone that causes a lot of pregnancy symptoms, including nausea," says Dr. Diamond. "So there may be a relationship with people who have false negative pregnancy tests (especially early on) and people who have few or no pregnancy symptoms, as both could be caused by low hCG levels." Further, she says, "Some pregnant people don't think to take a test at all because they do not have signs or symptoms."

Causes of Cryptic Pregnancy

While cryptic pregnancy can happen to anyone, it sometimes has a logical explantation. This can range from hormonal conditions to contraceptive methods to life changes. Dr. Boyer shares some possible causes of cryptic pregnancy.

Polycystic Ovarian Syndrome (PCOS): PCOS may limit your fertility, and it often causes irregular periods, weight gain, excessive oiliness of the skin, and digestive issues. Someone with PCOS may dismiss pregnancy symptoms as a complication of PCOS-induced hormonal imbalances.

Perimenopause: Pregnancy and perimenopause (a transition into menopause) have some overlapping symptoms, such as weight gain and mood changes. Women may think they're beginning a new stage of life instead of expecting a child. It's important to realize that you can get pregnant during perimenopause, even if you have an irregular cycle.

Birth Control Use: IUDs and birth control pills are very effective, but it's possible to conceive while using these contraceptive methods. If that happens, you may suffer from a false sense of security, not realizing you're actually pregnant until you're far into the gestation.

• RELATED: What Is False Pregnancy?

Intense Sports: Highly intensive activities and sports may also bring about hormonal fluctuations that can make it harder to detect a pregnancy. In addition, people in excellent physical condition are less likely to sport an obvious baby bump.

Thinking You Can't Get Pregnancy: If someone has an infertility diagnosis, they might not think it's possible to conceive. Similarly, women who are breastfeeding or recently gave birth might dismiss pregnancy symptoms if they didn't know ovulation returned yet.

One thing to note: In some cases, a cryptic pregnancy occurs because the pregnant person is in denial, or is experiencing a mental issue. "Some cases of cryptic pregnancy occur in the setting of mental illness (and denying that one is pregnant despite signs of pregnancy is a more prominent feature), but this is not the case by any means for most cryptic pregnancies," says Dr. Diamond.

Possible Complications of Cryptic Pregnancies

Because cryptic pregnancies progress without proper medical care, they increase the risk of complications for Mom and Baby. Fetal abnormalities and maternal health conditions (like preeclampsia or gestational diabetes) might go unnoticed. Parents-to-be might also use alcohol or drugs, which isn't considered safe while expecting. Unnoticed pregnancies have been associated with a higher risk of prematurity, low birth rate, hospitalization, unattended delivery, or death.

A new parent's mental health might also be affected by cryptic pregnancy, especially if they aren't prepared for a baby. This could lead to child abuse or neglect, disassociation from the baby, depression, and other signs of psychological distress.

• RELATED: How to Take the Most Accurate Pregnancy Test

The Bottom Line

While cryptic pregnancies may be hard to comprehend, they do happen on rare occasions. It's important to seek proper medical care if you experience any unexplained pregnancy-related symptom, even if you received a negative home pregnancy test (and you're sexually active). Proper diagnosis and care increases the odds of a healthy parent, baby, and pregnancy.