While in the womb, the baby floats in the amniotic fluid. The amount of amniotic fluid is greatest at about 34 weeks (gestation) into the pregnancy, when it averages 800 mL. About 600 mL of amniotic fluid surrounds the baby at full term (40 weeks gestation).
Too much amniotic fluid is called polyhydramnios. This condition can occur with multiple pregnancies (twins or triplets), congenital anomalies (problems that exist when the baby is born), or gestational diabetes.
Abnormal amounts of amniotic fluid may cause the health care provider to watch the pregnancy more carefully. Removing a sample of the fluid through amniocentesis can provide information about the sex, health, and development of the fetus.
Ross MG, Beall MH. Amniotic fluid dynamics. In: Resnik R, Lockwood CJ, Moore TR, Greene MF, Copel JA, Silver RM, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 4.
The amount of amniotic fluid increases until about 36 weeks of pregnancy. At that time, it makes up about 1 quart. After that, the amount of amniotic fluid usually begins to decrease. Sometimes you can have too little or too much amniotic fluid. Too little fluid is called oligohydramnios. Too much fluid is called polyhydramnios. Either one can cause problems for a pregnant woman and her baby. Even with these conditions, though, most babies are born healthy.
Normal amniotic fluid is clear or tinted yellow. Fluid that looks green or brown usually means that the baby has passed the first bowel movement (meconium) while in the womb. (Usually, the baby has the first bowel movement after birth.)
If the baby passes meconium in the womb, it can get into the lungs through the amniotic fluid. This can cause serious breathing problems, called meconium aspiration syndrome, especially if the fluid is thick. Some babies who have been in amniotic fluid that has meconium in it may need treatment right away after birth to prevent breathing problems. Other babies are healthy at birth may not need treatment, even if the amniotic fluid has meconium in it.
Amniocentesis is used to determine the health of an unborn baby. Amniotic fluid contains cells that are normally shed from the fetus. Samples of these cells are obtained by withdrawing some amniotic fluid. The chromosome analysis of these cells can be performed to determine abnormalities. In addition, the cells may be cultured and analyzed for enzymes, or for other materials that may indicate genetically transmitted diseases. Other studies can be done directly on the amniotic fluid including measurement of alpha-fetoprotein.
Amniotic fluid surrounds the growing fetus in the womb and protects the fetus from injury and temperature changes. It also allows for freedom of fetal movement and permits musculoskeletal development. The amniotic fluid can be withdrawn in a procedure called amniocentesis to check for chromosomal defects or other abnormalities.
Amniotic fluid has many important functions and is vital for healthy fetal development. However, if the amount of amniotic fluid inside the uterus is too little or too great, complications can occur.
While a baby is in the womb, it is situated within the amniotic sac, a bag formed of two membranes, the amnion, and the chorion. The fetus grows and develops inside this sac, surrounded by amniotic fluid.
Meconium in the fluid can be problematic. It can cause a breathing problem called meconium aspiration syndrome that occurs when the meconium enters the lungs. In some cases, babies will require treatment after they are born.
This may be evident in cases of leaking fluid from a tear in the amniotic membranes, measuring small for a certain stage of pregnancy or if the fetus is not moving as much as it would be expected to.
In some cases, doctors may decide that labor will need to be induced, in order to protect the mother or the child. Amnioinfusion (the infusion of saline into the uterus), increasing maternal fluids, and bed rest may also be necessary.
Sometimes, fluid leaks before the waters break. According to the American Pregnancy Association, only 1 in 10 women will experience a dramatic flow of fluid as the waters break. For most, it will start as a trickle, or leak.
Low amniotic fluid, also called oligohydramnios, is a serious condition. It happens when the amount of amniotic fluid is less than expected for a baby's gestational age. There's no treatment that can completely correct this condition. But short-term treatment options are available and can be helpful in certain situations.
If you are diagnosed with low amniotic fluid, what happens next will depend on what's causing the fluid to be low and how severe it is. Your baby's gestational age, your health and your baby's health will be taken into consideration too.
If you have low amniotic fluid during labor, your health care provider might consider a procedure in which saline is put into your uterus via a catheter placed through the cervix. This procedure is called amnioinfusion. It's typically done during labor if the health care team detects problems with the baby's heart rate.
The amniotic fluid is the protective liquid contained by the amniotic sac of a gravid amniote. This fluid serves as a cushion for the growing fetus, but also serves to facilitate the exchange of nutrients, water, and biochemical products between mother and fetus.
Amniotic fluid is present from the formation of the gestational sac. Amniotic fluid is in the amniotic sac. It is generated from maternal plasma, and passes through the fetal membranes by osmotic and hydrostatic forces. When fetal kidneys begin to function around week 16, fetal urine also contributes to the fluid. In earlier times, it was believed that the amniotic fluid was composed entirely of fetal urine.
The fluid is absorbed through the fetal tissue and skin. After 22 to 25 week of pregnancy, keratinization of an embryo's skin occurs. When this process completes around the 25th week, the fluid is primarily absorbed by the fetal gut for the remainder of gestation.
The forewaters are released when the amnion ruptures. This is commonly known as the time when a woman's "water breaks". When this occurs during labour at term, it is known as "spontaneous rupture of membranes". If the rupture precedes labour at term, however, it is referred to as "pre-labour rupture of membranes". Spontaneous rupture of membranes before term is referred to as "premature rupture of membranes". The majority of the hindwaters remain inside the womb until the baby is born. Artificial rupture of membrane (ARM), a manual rupture of the amniotic sac, can also be performed to release the fluid if the amnion has not spontaneously ruptured.
Swallowed amniotic fluid (in later stages of development) creates urine and contributes to the formation of meconium. Amniotic fluid protects the developing fetus by cushioning against blows to the mother's abdomen, allowing for easier fetal movement and promoting muscular/skeletal development. Amniotic fluid swallowed by the fetus helps in the formation of the gastrointestinal tract. It also protects the fetus from mechanical jerks and shocks. The fetus, which develops within a fluid-filled amniotic sac, relies on the placenta for respiratory gas exchange rather than the lungs. While not involved in fetal oxygenation, fetal breathing movements (FBM) nevertheless have an important role in lung growth and in development of respiratory muscles and neural regulation. FBM are regulated differently in many respects than postnatal respiration, which results from the unique intrauterine environment. At birth, the transition to continuous postnatal respiration involves a fall in temperature, gaseous distention of the lungs, activation of the Hering-Breuer reflex, and functional connectivity of afferent O2 chemoreceptor activity with respiratory motoneurons and arousal centers.
Analysis of amniotic fluid can reveal many aspects of the baby's genetic health as well as the age and viability of the fetus. This is because the fluid contains metabolic wastes and compounds used in assessing fetal age and lung maturity, but amniotic fluid also contains fetal cells, which can be examined for genetic defects.
Too little amniotic fluid is called oligohydramnios. In a minority of cases it can be a cause of problems for the mother and baby. These include contracture of the limbs, clubbing of the feet and hands, and also a life-threatening condition called hypoplastic lungs. The Potter sequence refers to a constellation of findings related to insufficient amniotic fluid.
Recent studies show that amniotic fluid contains a considerable quantity of stem cells. These amniotic stem cells are pluripotent and able to differentiate into various tissues, which may be useful for future human application. Some researchers have found that amniotic fluid is also a plentiful source of non-embryonic stem cells. These cells have demonstrated the ability to differentiate into a number of different cell-types, including brain, liver and bone. 041b061a72