Prenatal Screening Tests

What are prenatal screening tests?

“Prenatal screening tests” is a blanket term that covers a variety of testing your doctor may recommend or you may choose to have during pregnancy.

进行了一些产前筛查测试，以确定婴儿是否可能患有特定的健康状况或染色体异常，例如唐氏综合症。

您的医生很可能在您的第一个产前预约中提到了这些筛查测试，因为大多数是在第一和第二个三个中的筛选测试。

这种类型的筛选测试只能提供您特定条件存在的风险或概率。它不能保证会发生一些事情。它们通常是无创和可选的，尽管大多数OBS都建议使用。

When the results are positive, further diagnostic tests — some that may be more invasive — can provide more definitive answers for you and your doctor.

Other prenatal screening tests are routine procedures that look for health issues that may affect you, your pregnancy, or your baby. One example is theglucose tolerance test，检查妊娠糖尿病- 顺便说一句，这是可以管理的。

通常会提供额外的筛查测试，患有某些疾病的孩子的风险更高。例如，如果您住在结核病常见的地区，您的医生可能会订购结核蛋白（TB）皮肤测试。

何时进行产前筛查测试？

First trimester screening tests can begin as early as 10 weeks. These usually involve blood tests and an ultrasound. They test your baby’s overall development and check to see if your baby is at risk for genetic conditions, such as Down syndrome.

他们还检查您的宝宝是否有心脏异常，囊性纤维化和其他发育问题。

这一切都很沉重。但是，对于许多人来说，更令人兴奋的是，这些超级早期筛选测试也可以确定宝宝的性爱。具体来说，可以告诉您您是否有男孩或女孩的血液抽血是非侵入性产前测试（NIPT）

The NIPT blood draw isn’t available at all doctor’s offices, and your healthcare provider可能不提供it, depending on your age and other risk factors. But if you’re interested in this option, be sure to ask!

妊娠中期screening tests may occur between 14 and 18 weeks. They can involve a blood test, which tests whether you’re at risk for having a child with Down syndrome or neural tube defects.

超声波检查使技术人员或医生可以仔细看婴儿的解剖结构，通常在18到22周之间进行。

如果这些筛查测试中的任何一个显示出异常结果，则可能会有后续屏幕或诊断测试，可为您的医生提供有关宝宝的更多详细信息。

First trimester screening tests

Ultrasound

An ultrasound uses sound waves to create an image of the baby in the uterus.

The test is used to determine the size and position of your baby, confirm how far along you are, and find any potential abnormalities in the structure of your baby’s growing bones and organs.

在怀孕的第11周和14周之间进行了一种特殊的超声，称为颈部半透明超声。这种超声检查了婴儿脖子背面的液体积聚。

当比正常情况更多的流体时，这意味着唐氏综合症的风险更高。（但这不是结论性的。）

早期血液检查

During the first trimester, your doctor can order two types of blood tests called a sequential integrated screening test and a serum integrated screening.

They’re used to measure the levels of certain substances in your blood, namely, pregnancy-associated plasma protein-A and a hormone called human chorionic gonadotropin.

这两种异常水平意味着染色体异常的风险更高。

At your first prenatal visit, your blood may also be tested to see if you’re immunized against rubella and to screen for syphilis, hepatitis B, and HIV. Your blood will also likely be checked for贫血。

A blood test will also be used to check your blood type and Rh factor, which determines yourRh compatibilitywith your growing baby. You can be either Rh-positive or Rh-negative.

Most people are Rh-positive, but if you’re Rh-negative, your body will produce antibodies that will affect any subsequent pregnancies.

When there’s an Rh incompatibility, most women will be given a shot of Rh-immune globulin at 28 weeks and again a few days after delivery.

如果女性具有RH-Condative，并且她的婴儿是RH阳性的，则会发生不相容。如果这个女人是Rh-Conngative，并且她的孩子的阳性，她将需要射击。如果她的孩子是Rh-Condgative，她就不会。

注意：直到出生后，才有一种无创的方法来确定宝宝的血型。

Chorionic villus sampling

绒毛膜绒毛采样（CVS）是一种侵入性筛查测试，涉及从胎盘中取出一小块组织。您的医生可能会在较早的无创屏幕上的异常结果后建议该测试。

It’s usually performed between the 10th and 12th weeks and is used to test for chromosomal abnormalities, like Down syndrome, and genetic conditions, such as cystic fibrosis.

There are two types of CVS. One type tests through the belly, which is called a transabdominal test, and one type tests through the cervix, which is called a transcervical test.

Testing has some side effects, like cramps or spotting. There’s also a small risk of miscarriage. This is an optional test — you don’t have to get it done if you don’t want to.

妊娠中期screening tests

Ultrasound

During the second trimester, a more detailed ultrasound, which is often called a fetal anatomy survey, is used to evaluate the baby carefully from head to toe for any developmental issues.

While a second-trimester ultrasound can’t rule out all potential issues with your baby — that’s what the additional screens described below can assist with — it’s helpful for your OB to eyeball baby’s body parts, and fun for you to see those fingers and toes, too!

Blood tests

AQuad标记筛选测试是在妊娠中期进行的血液检查。它可以帮助您的医生学习是否增加了患有唐氏综合症，神经管缺陷和腹部壁异常的婴儿的风险。它测量了四种胎儿蛋白（因此，“ Quad”）。

A quad marker screening is typically offered if you start prenatal care too late to receive either the serum integrated screening or the sequential integrated screening.

除了顺序集成筛选测试或血清集成筛查测试外，它的检测率较低，其他问题的检测率较低。

Glucose screening

A glucose screening test checks for妊娠糖尿病, a condition that can develop during pregnancy. It’s usually temporary and resolves after delivery.

This glucose screening test is pretty standard for everyone, whether you’re considered high risk or not. And, note: You can develop gestational diabetes even if you’ve not had diabetes before your pregnancy.

Gestational diabetes can increase your potential need for acaesarean deliverybecause babies of mothers with gestational diabetes are usually born larger. Your baby may also have low blood sugar in the days following delivery.

Some doctors’ offices start with a shorter glucose screening, where you’ll drink a syrupy solution, have your blood drawn about an hour later, and then have your blood sugar levels checked.

If your levels are high, your doc will schedule a longer glucose tolerance test, where you’ll fast before the procedure, have your blood drawn for a fasting blood sugar level, drink a sugary solution, then have your blood levels checked once an hour for three hours.

Some doctors prefer to solely perform the longer glucose tolerance test. And this longer one may be performed if you have certain risk factors for gestational diabetes.

If you do test positive for gestational diabetes, you have a higher risk of developing diabetes within the following 10 years, so you should get the test again after the pregnancy.

羊膜穿刺术

Duringamniocentesis, you’ll have amniotic fluid removed from your uterus for testing. Amniotic fluid surrounds the baby during pregnancy. It contains fetal cells with the same genetic makeup as the baby, as well as various chemicals produced by the baby’s body.

An amniocentesis tests for genetic abnormalities, such as Down syndrome and spina bifida. A genetic amniocentesis is usually performed after week 15 of the pregnancy. It may be considered if:

• a prenatal screening test showed abnormal results
• you had a chromosomal abnormality during a previous pregnancy
• 您35岁或以上
• you have a family history of a specific genetic disorder
• you or your partner is a known carrier of a genetic disorder

Third trimester screening test

b组Strep screening

b组Streptococcus(GBS)是一种细菌，会引起孕妇和新生儿的严重感染。在健康女性中，通常在以下领域发现了GBS：

• mouth
• throat
• 下肠道
• 阴道

无论您怀孕，阴道中的GBS通常对您没有任何有害。但是，这对于一个阴道出生并且还没有强大的免疫系统的新生婴儿可能非常有害。GB会引起出生过程中暴露的婴儿的严重感染。

You can be screened for GBS with a swab taken from your vagina and rectum at 36 to 37 weeks. If you test positive for GBS, you’ll receive antibiotics while you’re in labor to reduce your baby’s risk of contracting a GBS infection.

与您的医生交谈

Prenatal screening tests can be an important source of information for pregnant people. While many of these tests are routine, some can be a much more personal decision.

与您的医生交谈about your concerns if you’re not sure if you should be screened or if you’re feeling anxious. You can also ask to be referred to a genetic counselor.

Your healthcare team can discuss the risks and benefits with you and help you decide which prenatal screenings are right for you.