Increases in AFP during pregnancy

Increases in AFP during pregnancy


Increased AFP or alpha phytoprotein is associated with fetal structural anomalies, some of which are listed below:

A) Nervous system disorders or NTDs

The neural tube is the part of the fetus that becomes the brain and spinal cord, the back of the skull, and the back of the vertebrae. If the fetus does not develop normally, the baby may be born with defects in these areas.

What are the defects of the neural tube?

The baby's central nervous system, like a flat screen, begins in the cells and enters a tube when it is complete. The front of the tube, which closes around day 23 of the fetal life, becomes the brain.

 The other end of the tube, which closes around day 28 of the fetal life, becomes the lower end of the spinal cord. If for any reason neither of these two ends is closed, a defect in the neural tube will occur.

1- The most common type is open neural tube defects, in which the brain and spinal cord are exposed to the external environment through a gap in the skull or vertebrae, and its well-known examples are:

 Open spina bifida, or myelomeningocele, anencephaly, and encephalocele, which are diagnosed with an increase in AFP.

 AFP detection power is 90% for open spina bifida and 98% for anencephaly detection.

Rare cases are closed-type nerve disorders [closed NTDs] in which the spinal cord is covered by a layer of skin and the most famous examples are:

Lipomyelomeningocele, lipomeningocele, and neurological disorders caused by deformity of the spinal cord (tethered cord) (not diagnosed by AFP).

B) Abdominal wall disorders [2] such as gastroesophageal reflux disease [3] (a type of abdominal wall hernia with severe AFP increase that can be treated after birth) and encephalocele. [4], congenital kidney disorders, esophageal atresia and any condition that causes distress Be annoyed, such as threatened abortion and fetal demise

C) Tratoma [5] (tumors of stem cell origin)

D) Hygroma cysts. [6] (Multifocal disorders of lymph nodes)


One in every 1,000 babies born in the United States has a neural tube defect. The incidence is higher in the UK and lower in Japan. The reason for the difference in percentages in different countries is not clear.

Prevention of neural tube defects in infants
The causes of neural tube defects are unclear, but it has been shown that if a woman consumes a small amount of folic acid once a month before pregnancy and during the first trimester of pregnancy, her baby's chances of developing neural tube defects are reduced.

 In early pregnancy, fetal tests, such as blood tests and ultrasounds, usually identify neural tube defects. If the defect is severe or the child is unlikely to survive, the couple can decide to have an abortion.

If you or your child's father have a family history of neural tube defects, or are taking anticonvulsant pills, or have diabetes, talk to your doctor about it before you become pregnant.

Some studies show that being obese increases the risk of neural tube defects in the baby, so it's best to reach your ideal weight before trying to conceive.

Treatment of neural tube defects in infants
In mild neural tube defects, sometimes no symptoms may occur and no treatment is needed. For more severe cases, surgical treatment is required.

For example, in hydrocephalus or accumulation of fluid in the brain (brain drain), the tube is inserted into the brain and the fluid is expelled. However, the child may be permanently disabled.

 In this case, sports therapy is prescribed for the child and they will help him to continue his life despite his disability.

Screening for neonatal nerve cord disorders
An AFP marker measurement is used for the second trimester to screen for nerve cord disorders. The marker is first synthesized by the yolk sac and then by the liver and is produced in small amounts by the fetal digestive tract.

 By the end of the first trimester, almost all of the AFP is produced by the fetal liver. The highest serum AFP levels in the fetus are between 11 and 13 weeks. This protein crosses the blood-placental barrier and enters the mother's bloodstream, and very little enters the amniotic cavity. Its level in the mother's blood increases to 26 to 32 weeks per week and reaches up to 250 ng / L. The fetus with open nerve rope disorders causes the direct release of AFP into the amniotic space and its concentration in amniotic fluid increases.

Its level in the mother's blood also increases. Second-trimester screening tests are highly sensitive (about 80%) to diagnosing these disorders. Nervous system disorders can be seen in two ways:

Normally, the AFP MoM is less than 2.5, and if the AFP MoM is greater than 2.5, the following is the following:

A) Two- or three-dimensional ultrasound: To confirm the age of the fetus, a diagnosis of being twins or anencephaly is made. (1% of pregnancies are twin pregnancies, of which 2.3 are diphtheria and 3.1% are meningococcal).

Note 1: The diagnostic power of AFP is 88% for encephalitis and 79% for open spina bifida. These disorders are usually detected on high-resolution ultrasound from 18 weeks onwards, but severe forms of encephalitis can be detected on ultrasound earlier than 16 weeks.

Note 2: AFP MoM with more than 5 with uE3 MoM less than 0.3 raises the possibility of encephalitis.

B) Repeat AFP measurement: AFP measurement 7-10 days after the first measurement in cases where AFP MoM is between 3.5-2.5 and fetal age less than 19 weeks.

 Repeat this test to prove the increasing trend of AFP levels due to open nerve rope disorders.

Note: In the following cases, it is not necessary to repeat the AFP test:

1- The age of the fetus is more than 19 weeks.

2. Screening test results are positive for Down syndrome.

3- AFP MoM is more than 3.5.

In 3.5% of pregnancies, AFP MoM is more than 2, and in 50% of cases, repeating this test after one week is a normal result and does not require further examination.

C) Genetic counseling: Because many genetic disorders lead to neurological disorders, genetic counseling and, if necessary, amniocentesis are recommended to check for chromosomal and genetic disorders and to measure the AFP of amniotic fluid.

If AFP is high in amniotic fluid, measurement of acetylcholinesterase (to prove AFP leakage from the nerve cord) is recommended. If the acetylcholinesterase of the amniotic fluid is positive, even if the ultrasound findings are normal, the diagnosis of neural tube defects will be made.

D) Following the normal results of amniocentesis and rejection of other maternal factors (such as ovarian tumors, race, smoking, blood relationship with husband, geographical area, anemia, fetal sex), placenta or fetus, high unexplained AFP with Increased risk is associated with adverse pregnancy outcomes and placental disorders (such as choriocarcinoma, [7] choriocarcinoma [8], and fetal death).

Adverse pregnancy outcomes following AFP increase include:

- Premature rupture of the bladder [9]

- Early childbirth [10]

- Premature labor pain

Weight-bearing birth [11]: A study by Dr. Katz and colleagues found that increasing AFP could increase the risk of low birth weight babies by 2 to 4 times, due to preterm labor or intrauterine growth restriction (IUGR). ) Occurs. Dr. Harley's study also found that if AFP increased with abnormal hCG levels (Mom> 2.5 or MoM

- Preeclampsia

- IUGR

Pair decollete: [14] AFP increases up to 10 times.

- Death

- IUFD

- Decreased amniotic fluid [15]

- Extensive bleeding during childbirth [16]

- Immaturity [17]

The etiology of increased AFP in these disorders is that the presence of any dysfunction or placental structure increases the transmission of AFP from the fetus to the mother's blood by causing a defect in the placental-blood barrier, resulting in increased AFP levels in the mother's blood.

Note 1: An unexplained increase in AFP with an abnormal finding in Doppler of the uterine artery [18] is associated with an increased risk of preeclampsia, preterm delivery, IUGR, and IUFD.

Note 2: If the AFP MoM level is between 2.5 and 2.9, the risk of adverse pregnancy outcomes increases to 19%, and if it reaches more than 5%, the risk increases to 70%.

Note 3: Elimination of the embryo in multiple cases [19]. Can significantly increase AFP levels (4 to 9 times the normal rate).

Note 4: Decreased AFP (MoM [20] (infant size) is associated.

Note 5: If the increase in AFP is associated with the report of placental abruption [21] in the first or second trimester ultrasound, there is a possibility of an increase in the occurrence of serious placental disorders such as placenta accreta, [22] placenta increta [23] and placenta percreta [24] .

Note 6: In cases of increased AFP, paired pathology examination is recommended for chorionic villitis and vascular lesions of the placenta. Because these disorders increase the likelihood of AFP leakage from fetal blood flow to the mother.

Note 7: Increased AFP is also seen in mothers with thrombophilic disorders.

Note 8: Increased AFP is associated with increased morbidity [25] in infants such as low apgar (scores 4 to 6), asphyxia [26], and fetal need for intensive care (need for hospitalization in neonatal intensive care unit).

Note 9: There has been a strong association between increased AFP levels and sudden infant death syndrome [27].] 19-14 [

Note 10: In twin embryos, the detection power of NTDs is reduced because if a fetus is normal, low AFP production in this embryo can cover the high concentration of AFP secreted by the second embryo and therefore it is better than the lower cut-off for pregnancy. Use twins.

Note 11: MSAFP measurement is not permitted in women with a BMI greater than or equal to 40.

Note 12: MSAFP measurements should be limited in women who do not have access to a quality scan anomaly, according to the 2016 Guideline Perinatal Services BC Obstetric Guide.

 Because in cases where the risk of nerve cord and abdominal wall disorders is in the high-risk area, it is not possible to follow up with a quality scan anomaly and only lead to stress and anxiety in the mother.



[1]. fetal structural anomalies

[2]. ventral or abdominal wall defects

[3]. gastroschisis

[4]. omphalocele

[5]. teratoma

[6]. cystic hygroma

[7]. choriocangioma

[8]. choriocarcinoma

[9]. Preterm Rupture Of Membranes (= PROM)

[10]. preterm delivery or birth

[11]. low birth weight

[12]. Katz

[13]. Harley

[14]. abruption placenta

[15]. oligohydroamnious

[16]. antepartum bleeding

[17]. prematurity

[18]. uterine artery Doppler

[19]. transabdominal multifetal reduction

[20]. macrosomia

[21]. placenta previa

[22]. placenta accreta

[23]. placenta increta

[24]. placenta percreta

[25] . morbidity

[26]. asphyxia

[27]. sudden infant death syndrome