What should my afi be at 36 weeks

If people have any symptoms of low or high amniotic fluid levels, they should arrange a checkup with their healthcare team. Ultrasounds can help to check amniotic fluid levels, and close monitoring and treatment can ensure both the pregnant woman and the fetus stay healthy.

Having too much amniotic fluid during pregnancy can result in an early or difficult delivery. It can also increase the risk to the baby. A doctor may…. Amniotic fluid is the fluid that surrounds and protects an embryo while it is growing in the uterus.

It is essential for fetal development. A developing child survives for around 9 months without coming into contact with the outside world. How do babies breathe in the womb?

This MNT…. L-arginine is an amino acid that helps the body to build proteins. Athletes and others seek out ways to boost their L-arginine intake. It may have…. Many women experience an increase in vaginal discharge during pregnancy or find that they leak urine at times. However, a clear and odorless fluid…. Tips on how to increase amniotic fluid. Is it possible? Tips and methods Complications Seeing a doctor Summary Amniotic fluid supports a developing fetus in the womb during pregnancy.

Increasing amniotic fluid levels. Share on Pinterest Increasing water intake may help improve amniotic fluid. How to increase amniotic fluid. High or low levels of amniotic fluids. When to see a doctor. Latest news Adolescent depression: Could school screening help? Exposure to air pollutants may amplify risk for depression in healthy individuals. The maximum value of AFI in any single patient was If minimum 5th centile and maximum 95th centile are considered as normal range, it was noted that the corresponding values too were different at different gestational ages; the more advanced the gestational age, the lesser the values.

These changes are graphically represented in Figure 1. AFI values from 34 to 40 weeks; mean, standard deviation, and percentile values all in centimeters. We used difference in mean values of one week to the next week to evaluate the decreasing trend of amniotic fluid from 34 to 40 weeks of gestation Table 2. Dark shaded area indicates cells where calculations are not required as they are the same weeks or previous weeks. It can be seen that many cells have the values less than 1, but still the difference may be calculated statistically significant if ordinary statistical tests such as paired t test were applied and hence we have used Cohen's test which very well detects the magnitude of change.

Table 3 indicates Cohen's d values for week to week comparison and it can be seen that not much change was seen in immediate week, but changes became significant when the interval between two scans was more than 2 weeks or more in most of the comparisons. Hence from this table there is substantial evidence that liquor volume decreases significantly over the period of 14 days more in low risk antenatal women.

Our results indicated that from 34 weeks onwards there is a gradual reduction in AFI. Using polynomial regression analysis, we have established reference standards for AFI ranges from 34 to 40 weeks Figure 2. Curve of AFI values 5th, 50th, and 95th centiles from 34 to 40 weeks following smoothing procedure from polynomial regression of 3rd degree.

The following equations were derived by third degree polynomial regression using y AFI in cm as dependent variable and x gestation age in weeks as independent variable, where Y 5th , Y 50th , and Y 95th indicate 5th, 50th, and 95th centile values for AFI and GA indicates gestational age in weeks:. Amniotic fluid production and regulation is a complex and dynamic process involving the fetus, placenta, and mother. Amniotic fluid volume gradually increases till 32—34 weeks of gestation and thereafter there is a gradual reduction till term [ 18 , 19 ].

The third trimester AFI values are proportionate to fetal urine production [ 20 , 21 ] and hence in normal range indicate good placental perfusion and fetal nutrient and oxygen transfer. Hence monitoring the AFI has become a standard of antenatal care. There is wide variation in reference standards for mean AFI values according to population, race, and geography.

Table 4 compares our finding with that of other authors [ 16 , 22 — 25 ]. We have also graphically interpreted findings in the other studies either mean or 50th percentile values in Figure 3. However, it is noticeable that majority of the studies agree that from 34 weeks onward there is a gradual fall in AFI values. The two studies [ 16 , 25 ] are from India, but the reported AFI range has a wide range. This may be because their observations were based upon retrospective cross sectional data.

It is noticeable that AFI reference values published by Singh et al. Hence, it can be opined that AFI standards have to be defined for specific populations in order to eliminate bias resulting from socioeconomic groups, geographical locations, race, and so forth. However, it must be noted that almost all authors have reported a steady decline in AFI values with the advancing gestational age, except Birang et al.

Their series included retrospective cross sectional data and the number differed from minimum of 12 observations at 35 weeks to maximum of 68 observations at 39 weeks. This might be the reason for their finding of rapid fall of AFI from 34 to 35 weeks, plateauing between 37 and 39 weeks and once again slow fall at 40 weeks.

Such observations indicate weakness of cross sectional cohort, as the same patients are not followed up sequentially. Amniotic fluid once thought to be a stagnant pool with approximate turn over time of twenty-four hours. In high risk pregnancies complicated by chronic placental insufficiency liquor is known to drastically reduce in a shorter time and it has been recommended to perform AFI estimation once in three days or at times even frequently depending upon other fetal well-being surveillance tools such as Doppler assessment of fetal circulation.

However, there is no universal consensus regarding the frequency of AFI estimation in low risk antenatal women. Hence, it is important to determine a critical interval at which the fall in AFI becomes clinically significant.

We have not used statistical significance test involving estimation of P value such as paired t test for comparing AFI values at different gestational ages, as these tests tend to give significant P values even when a minor variation exists in the means of two groups. When sample size is sufficiently large, even the fractional differences are likely to be reported as significant P values, hence giving meaningless interpretations. Instead, we have calculated effect size estimate Cohen d to quantify the changes in the AFI over a period of time.

Effect size is a simple measure for quantifying the difference between two groups or the same group over time, on a common scale. There are several methods mentioned in the literature to calculate the effect sizes Cohen [ 17 ], Rosenthal and Rosnow [ 26 ], Partial Eta squared Richardson [ 27 ] and so forth.

However, we have used Cohen's d estimate as described by Cohen , to calculate effect sizes as this method is easy, simple to understand and can be applied to any measured outcome in scientific study.

From our statistical analysis, we have found that there is no much decrease in AFI at interval of one week, but thereafter the differences become large and significant.

Hence, it appears that when the liquor is within normal range, the chances of fetal jeopardy are unlikely to occur within next week; one can safely repeat the AFI after 2 weeks. At the time of estimation of AFI, one can also perform other tests for foetal well-being such as documentation of gross foetal body movements, foetal tone, and foetal breathing movements to be assured that foetus is not hypoxic.

In addition, interval biometry may be done at whenever required to quantify satisfactory foetal growth. In the absence of any maternal or foetal risk factors, we are of the opinion that AFI estimation once in fortnight is good enough to ensure satisfactory pregnancy outcome. We have established not only gestational specific normative AFI reference standards for late third trimester 34 to 40 weeks for our local population but also magnitude of change in AFI values at weekly interval by quantitative analysis using effect size statistics.

Strength of present study is that it is based on longitudinal data of normal healthy pregnant women and percentile curves obtained can be used to define what constitutes normal range of AFI for low risk antenatal patients. Though our results are based on required number of patients by sample size determination, larger number of subjects if studied may yield robust reference curves for AFI and identify extreme values to define what constitutes oligo- or polyhydramnios.

The same study can be extended to high risk pregnancies such as preeclampsia, chronic hypertension, multiple gestation, and intrauterine growth restriction, in order to determine the frequency of liquor testing for these cohorts.

National Center for Biotechnology Information , U. Journal List J Pregnancy v. J Pregnancy. Published online Jan Author information Article notes Copyright and License information Disclaimer.

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

This article has been cited by other articles in PMC. Abstract Background. Introduction The ultimate goal of antepartum surveillance program is to improve perinatal outcome and to decrease intrauterine fetal demise besides prevention of maternal morbidity and mortality [ 1 , 2 ].

Aims and Objectives The purpose of the present investigation is to study the pattern of change in AFI on weekly basis from 34 weeks till delivery; to constitute reference ranges of AFI from 34 to 40 weeks of gestation; to find the time interval by which there is a significant fall in AFI, which will help obstetrician to plan an ideal protocol for antenatal ultrasound examination in the third trimester.

Sample Size Estimation Khadilkar et al. Open in a separate window. Figure 1. Graphical representation of AFI centiles at various gestational ages. Table 1 AFI values from 34 to 40 weeks; mean, standard deviation, and percentile values all in centimeters. Gestational age Mean Standard deviation 5th percentile 10th percentile 50th percentile 90th percentile 95th percentile 34 weeks Table 2 Mean change in AFI cm values at different intervals. From To 35 weeks 36 weeks 37 weeks 38 weeks 39 weeks 40 weeks 34 weeks 0.

Table 3 Cohen d coefficients of effect size at different intervals. Comparison not done. Figure 2. Discussion Amniotic fluid production and regulation is a complex and dynamic process involving the fetus, placenta, and mother. Figure 3. Comparison of AFI values at different gestational ages in various studies.

Table 4 Values of AFI in cm by different authors. Dev Thank you for updating your details. Log In. Sign Up.

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