Standard value of amniotic fluid for each gestational week

When the fetus grows in the uterus, it needs amniotic fluid. The amount of amniotic fluid is very important for the growth and development of the fetus. Whether the amniotic fluid is too much or too little, it will affect the healthy growth of the fetus. If you want the fetus to grow healthily, you need to keep the amniotic fluid within a normal range at different stages of pregnancy. Regularly going to the hospital for check-ups can help you find out whether the amount of amniotic fluid is normal in time and avoid abnormal amniotic fluid affecting the health of the fetus.

Standard value of amniotic fluid for each gestational week

First month (4 weeks): The fetus's brain, eyes, mouth, inner ears, digestive tract, hands, and feet have taken shape. The fetus is about half a centimeter long and has a small amount of amniotic fluid.

Second month (8 weeks): The fetus's face, elbows, knees, fingers and toes begin to form, and bones begin to develop. The fetus is already moving slightly, is about 3 cm long, weighs about 1 gram, and has a small amount of amniotic fluid.

Third month (12 weeks): At this time, the fetus in the uterine cavity can kick, clench fists, turn head, squint eyes and frown. Teeth, lips, and genitals begin to develop. The fetus is about 9 cm long and weighs about 28 grams. B-ultrasound showed that the biparietal diameter was 3.0 ~ 3.2 cm, the humerus was 1.03 cm, the femur was 1.56 cm, the chest circumference was 6.43 cm, the abdominal circumference was 7.4 cm, and the amniotic fluid index was 7.87 cm.

Fourth month (16 weeks): At 16 weeks of pregnancy, the fetus' hair, eyes, eyelashes, and nails begin to grow, and the vocal cords and taste buds have grown. The fetus is now about 18 cm long and weighs 113 g. B-ultrasound showed that the biparietal diameter was 3.28 ~ 3.6 cm, humerus 1.75 ~ 2.0 cm, femur 2.03 ~ 2.23 cm, chest circumference 8.43 cm, abdominal circumference 9.40 cm, and amniotic fluid index 10.5 cm.

Fifth month (20 weeks): At 5 months of pregnancy, fetal movements begin to become stronger. The fetus has grown hair and can suck its thumb, and organs in various parts of the body gradually grow. At this time, the fetus is about 25 cm long and weighs 224 to 500 grams. B-ultrasound showed that the biparietal diameter was 4.47 ~ 5.0 cm, humerus was 2.57 ~ 2.97 cm, femur was 3.01 ~ 3.47 cm, chest circumference was 11.71 ~ 12.7 cm, abdominal circumference was 13.41 ~ 15.2 cm, and amniotic fluid index was 12.4 ~ 14.7 cm.

Sixth month (24 weeks): At 24 weeks of pregnancy, the fetus' eyes can open and close, and can hear sounds inside the mother's body. The fetus' body is already 29 to 30 cm long and weighs 680 to 1000 grams. B-ultrasound showed: biparietal diameter 5.73 ~ 6.07 cm, humerus 3.72 ~ 4.3 cm, femur 4.2 ~ 4.75 cm, chest circumference 14.9 ~ 16.4 cm, abdominal circumference 16.84 ~ 17.5 cm, amniotic fluid index 14.3 ~ 15.9 cm.

Seventh month (28 weeks): At 28 weeks of pregnancy, the fetus gains rapid weight, about double that of 24 weeks. The skin is red and slightly wrinkled. The weight is about 1150g ~ 1800g and the body length is 35 ~ 42cm. B-ultrasound showed: biparietal diameter 6.64 ~ 7.01 cm, humerus 4.39 cm, femur 5.27 cm, chest circumference 17.37 cm, abdominal circumference 19.35 cm, amniotic fluid index 15.2 ~ 17 cm.

Eighth month (32 weeks): At 32 weeks, the fetus gradually grows, and its bones and internal organs become more mature and strong. At this time, the fetus can already hear sounds outside the mother's body. The body length is 42 to 46 cm and the weight is 2 to 2.7 kg. B-ultrasound showed: biparietal diameter 7.79 ~ 8.18 cm, humerus 5.54 cm, femur 6.55 cm, chest circumference 22.3 cm, abdominal circumference 25.36 cm, amniotic fluid index 15 ~ 16 cm.

Ninth month (36 weeks ~ 40 weeks): The fetus has reached near maturity, with pink skin, plump subcutaneous fat, and the skin surface covered with vernix caseosa. The fetal head descends into the pelvis. Be prepared for the birth. At this time, the fetus is 50 to 55 cm long and weighs about 2.8 to 3.6 kg. B-ultrasound showed that the biparietal diameter was 8.40 ~ 9.31 cm, humerus 5.59 ~ 6.29 cm, femur 6.76 ~ 7.62 cm, chest circumference 23.05 ~ 24.32 cm, abdominal circumference 25.89 ~ 28.11 cm, and amniotic fluid index 15.6 ~ 14.6 cm.