Introduction

Amniotic fluid is essential for normal fetal development.

The volume of amniotic fluid changes as the fetus grows. From the 10th to the 20th week, it increases markedly and continues to increase until about 28 weeks, after which the volume slowly reduces.

Fetal urine production contributes to the amniotic fluid after the kidneys begin working late in the first trimester.

Amniotic fluid is both 'breathed' and swallowed by the fetus. The 'breathing' of the fluid is essential for normal lung development. The fluid also cushions the developing baby, allows for easier fetal movement and promotes muscular/skeletal development.

Abnormality of amniotic fluid

Abnormality of the amniotic fluid volume may have a number of effects and a number of causes:

Too much fluid is called polyhydramnios and too little fluid oligohydramnios.

Lung development may be affected if there is too little fluid and it may also contribute to the development of some abnormalities of the skeleton such as club foot.

Too much fluid can cause over-distension of the uterus and lead to premature labour.

If the amniotic fluid is in excess of the normal range, this can be due to diabetes, fetal heart disease, fetal anaemia or problems with baby’s digestive tract. If the amniotic fluid is below normal range, this can be due to rupture of membranes, problems with baby’s kidneys or growth retardation.

Top