RESEARCH ARTICLE


https://doi.org/10.5005/jp-journals-10006-1985
Journal of South Asian Federation of Obstetrics and Gynaecology
Volume 13 | Issue 6 | Year 2021

Amniotic Fluid Optical Density in Spontaneous Onset of Labor and Elective Termination of Pregnancies beyond 34 Weeks of Gestation and Its Correlation with Neonatal Outcome

Mohita Agarwal1, Asha Nigam2, Abhilasha Yadav3, Sana Ismail4, Ruchika Garg5

1–5Department of Obstetrics and Gynaecology, Sarojini Naidu Medical College, Agra, Uttar Pradesh, India

Corresponding Author: Sana Ismail, Department of Obstetrics and Gynaecology, Sarojini Naidu Medical College, Agra, Uttar Pradesh, India, Phone: +91 9068995755, e-mail: ismailsana8@gmail.com

How to cite this article: Agarwal M, Nigam A, Yadav A, et al. Amniotic Fluid Optical Density in Spontaneous Onset of Labor and Elective Termination of Pregnancies beyond 34 Weeks of Gestation and Its Correlation with Neonatal Outcome. J South Asian Feder Obst Gynae 2021;13(6):422–425.

Source of support: Nil

Conflict of interest: None

ABSTRACT

Aim and objective: To measure the AFOD levels in cases with spontaneous onset of labor and elective termination of pregnancies before term and after term and its correlation with the neonatal outcome.

Materials and methods: This study was conducted in the labor room of Department of Obstetrics and Gynaecology in SN Medical College, Agra. One hundred antenatal patients fulfilling the inclusion and exclusion criteria were selected for the study and divided into two groups.

Results: In our study no correlation between AFOD and gestational age and birth weight was observed and with AFOD <0.9 increased the chances of respiratory distress, NICU admissions, and low APGAR score, and increased perinatal morbidity and mortality was observed.

Conclusion: AFOD estimation is cheap, easily available; results can be obtained within few minutes; and helps to make quick decisions when compared to L/S ratio estimation.

Keywords: Amniotic fluid optical density (AFOD), Preterm labor, Respiratory distress syndrome (RDS)

INTRODUCTION

Prematurity is a global problem. It is the leading cause of neonatal mortality and long-term neurological morbidity.

India tops (23.6% of global burden) in the list of 10 nations contributing to 60% of world’s premature deliveries. Significant long-term neonatal/pediatric sequelae; respiratory, CNS and neurodevelopmental, blindness and deafness.

It is not an uncommon observation that few babies born preterm are fully functionally mature and do not develop RDS, whereas few babies born after term are functionally premature and develop RDS (Term RDS).

There are numerous occasions where it is necessary to know the functional maturity of a fetus. The problem is more significant when complications of pregnancy like placental insufficiency, toxemia, ante-partum hemorrhage, diabetes, rhesus isoimmunization threaten the life of the fetus in utero. A reliable estimate of fetal maturity is therefore mandatory before induction of labor.

Even though amniotic fluid L/S ratio estimation is the gold standard for lung maturity assessment but it has its disadvantages such as it is costly, cumbersome, and time-consuming, but AFOD estimation is cheap, bedside procedure, and results can be obtained within few minutes.

As this is an easy and a bedside procedure, no training and special skills are required for performing this procedure.

MATERIALS AND METHODS

Type of Study

Prospective hospital-based study.

One hundred cases were selected from the antenatal cases presenting to the labor room of Department of Obstetrics and Gynaecology in SN Medical College, Agra, who met the inclusion and exclusion criteria over a period of 18 months.

Before conducting the study proper consent of the patient was taken and patient was informed about the procedure. After detailed history and examination, these cases were divided into two groups: GROUP A: Spontaneous onset of labor which is further subdivided into A1—Between 34–37 weeks and A2—Beyond 37 weeks and GROUP B: Elective termination of pregnancies (by induction or cesarean section) which is further subdivided into B1—Between 34–37 weeks and B2—Beyond 37 weeks.

In Subjects in Labor

Amniotic fluid samples were collected when the cervix is 3–4 cm dilated and the bag of membranes is lying loose in between the uterine contractions under aseptic precautions with a soft plastic cannula attached to a 10 mL disposable syringe; 2–3 mL sample were collected.

During Cesarean Section

While making uterine incision avoiding injury to the bulging membranes amniotic fluid was collected using a soft plastic cannula attached to a 10 mL syringe before rupturing the membranes.

Inclusion Criteria

Cases beyond 34 weeks of gestation admitted in labor or being planned for induction.

Exclusion Criteria

  • Intrauterine fetal death

  • Meconium stained liquor

  • Blood stained liquor

  • Antepartum hemorrhage

  • Oligohydramnios/anhydramnios

  • Preterm premature rupture of membranes

  • Evidence of chorioamnionitis

  • Rh-negative pregnancy

  • Multiple pregnancies

RESULTS

In this prospective hospital-based study which was done on 100 antenatal women it was observed that there was no statistically significant difference in the groups in terms of age, obstetric history, the maximum cases in both the groups were multigravidae, more than half of the patients of both the groups were from rural area as depicted in Table 1. According to modified Kuppuswamy classification majority of patients belonged to lower class. Majority of patients in both the groups belonged to the gestational period of >37 weeks. No difference was seen in terms of gestational period in between both the groups (p = 0.0064). The maximum patients in both the groups had hemoglobin between 7.1 and 7.5 g/dL. Majority of patients had BMI between 25 and 29.9 in both the groups.

Table 1: Correlation of demographic, medical, and obstetric factors between spontaneous and elective group
  Spontaneous Elective
Mean age 27.86 ± 4.18 years 27.96 ± 4.03
Obstetric history Multigravidae Multigravidae
Residential area Rural area Rural area
Socioeconomic status Lower class Lower class
Mean gestational period >37 weeks >37 weeks
Mean hemoglobin 7.1–7.5 g/dL 7.1–7.5 g/dL
Mean BMI 25–29.9 25–29.9
Mean birth weight 2.6–3.0 kg 2.6–3.0 kg

In the spontaneous onset (group A) maximum patients had cesarean delivery in both the groups and maximum patients in elective termination (group B) have normal vaginal delivery having gestational period between 34 and 37 weeks and while in the patients with gestational period >37 weeks maximum patients had cesarean delivery. Maximum number of babies in both the groups had birth weight between 2.6 and 3.0 kg as shown in Table 1.

Majority of cases in both the groups were having AFOD <0.9 as shown in Figure 1; the mean AFOD in the spontaneous group was 1.0102 ± 0.2762 and the mean AFOD in the elective group was 0.9642 ± 0.2609. No statistically significant difference was observed in between both the groups (p = 0.3941) as seen in Table 2.

Fig. 1: Bar diagram shows correlation of amniotic fluid optical density with gestational period in both the groups

Table 2: Correlation of amniotic fluid optical density with gestational period in both the groups
AFOD Spontaneous Elective
34–37 weeks >37 weeks Total 34–37 weeks >37 weeks Total
<0.9 16 14 30 14 17 31
0.9–1.4 4 8 12 8 5 13
>1.5 2 6 8 6 0 6
Total 22 28 50 28 22 50
Mean ± SD 1.0102 ± 0.2762 0.9642 ± 0.2609
p value 0.3941

Correlation of respiratory distress with AFOD in both the groups is shown in Table 3. In the spontaneous group and elective group, cases with AFOD levels less than 0.9, 8, and 9 babies were having respiratory distress with gestational period between 34 and 37 weeks and 1 and 2 babies were having respiratory distress with gestational period of >37 weeks, respectively, and in cases with AFOD levels ≥1.5, no baby of gestational period between 34 and 37 weeks and >37 weeks was having respiratory distress in both the groups as shown in Table 3. It was observed that there were significant babies who had respiratory distress with AFOD <0.9 in both the groups.

Table 3: Correlation of respiratory distress with AFOD in both the groups
AFOD 34–37 weeks >37 weeks Total (N = 50) p value
Spontaneous
  <0.9 respiratory distress 8 1 9 0.0370
  0.9–1.4 respiratory distress 1 0 1 0.3197
  ≥1.5 respiratory distress 0 0 0 0.0113
Elective
  <0.9 respiratory distress 9 2 11 0.0150
  0.9–1.4 respiratory distress 0 1 1 0.3197
  ≥1.5 respiratory distress 0 0 0 0.0045

The correlation of birth weight with AFOD was studied as shown in Table 4. It was observed that in the spontaneous group and elective group cases with AFOD levels less than 0.9, 6 and 5 babies had a birth weight of ≤1.5, 16 and 12 babies had birth weight between 1.6–2.5, and 8 and 14 babies had birth weight >2.5 as shown in Figure 2, and in cases with AFOD levels between 0.9 and 1.4, 3 and 2 babies had a birth weight of ≤1.5, 4 and 7 babies had a birth weight between 1.6 and 2.5, and 5 and 4 babies had a birth weight of >2.5, and in cases with AFOD ≥1.5, no baby had a birth weight of ≤1.5, 2 and 1 babies had a birth weight between 1.6 and 2.5, and 6 and no babies had a birth weight of >2.5, respectively.

Fig. 2: Bar diagram shows correlation of amniotic fluid optical density with birth weight in both the groups

Table 4: Correlation of birth weight with AFOD in both the groups
AFOD   Birth weight Total p value
≤1.5 1.6–2.5 >2.5
≤0.9 Spontaneous 6 16 8 30 0.9196
  Elective 5 12 14 31  
0.9–1.4 Spontaneous 3 4 5 12 0.8580
  Elective 2 7 4 13  
≥1.5 Spontaneous 0 2 6 8 0.8295
  Elective 0 1 5 6  
Total Spontaneous 9 22 19 50  
  Elective 7 20 23 50  

The difference was statistically nonsignificant in between both the groups. No correlation between AFOD and birth weight was observed in between both the groups.

In Table 5, the correlation of NICU admissions with AFOD is shown. In the spontaneous group and the elective group cases with AFOD levels less than 0.9, 8 and 9 babies were admitted in NICU with gestational period between 34 and 37 weeks and 1 and 2 babies were having NICU admission with gestational period of >37 weeks; in cases with AFOD levels ≥1.5 no babies were having NICU admissions in both groups. It was observed that there were significant NICU admissions with AFOD <0.9 in both the groups.

Table 5: Correlation of NICU admission with AFOD
AFOD   34–37 weeks >37 weeks Total (N = 50) p value
Spontaneous
<0.9 NICU admission 8 1 9 0.0370
0.9–1.4 NICU admission 1 0 1 0.3197
≥1.5 NICU admission 0 0 0 0.0113
Elective
<0.9 NICU admission 9 2 11 0.0150
0.9–1.4 NICU admission 0 1 1 0.3197
≥1.5 NICU admission 0 0 0 0.0045

In our study no correlation between AFOD and gestational age was found, birth weight was observed, and with AFOD <0.9, increased chances of respiratory distress, NICU admissions, and low APGAR score and increased perinatal morbidity and mortality were observed.

DISCUSSION

The physiology of onset and progression of labor is undoubtedly multifactorial involving various rate-limiting complex sequential inter-related and mutually supportive cascades. A minor natural variation at any level can affect the duration of pregnancy. Some women have genetic predisposition to deliver preterm due to differences at molecular level. Noninfected “preterm” cervical ripening is an inflammatory process like that of term labor. Polymorphisms in several genes regulating cytokines1 genetic susceptibility to infections of low virulence, mutations of collagen synthesis, oxytocin receptors, BMI, parity, and age are also involved.2 These factors vary from race to race and also between each fetomaternal unit, resulting in physiological variation in duration of pregnancy.3,4

Klimek measured the functional maturity status of the newborn babies with clinical scoring system (Klimek’s maturation index) and reported that some babies attain completion of functional maturity early and in some the maturation process completes late.5,6 Further he observed, fetal functional maturity is a separate entity and it does not depend either on size, weight, or GA of the fetus.5,6 In our study no correlation between AFOD and mode of delivery, gestational age, and birth weight was observed.

In our study, with AFOD <0.9, increased chances of respiratory distress, NICU admissions, and low APGAR score and increased perinatal morbidity and mortality were observed and babies born with AFOD values <0.40 were functionally premature irrespective of gestational age and were likely to develop RDS and might require mechanical ventilation; similarly a study conducted by Ram et al. had shown that spontaneous onset of labor occurs at AFOD value 0.98 ± 0.27 (at 650 nm).7,8 At this AFOD value babies attain completion of functional maturity. On the other hand, a term baby even at 40 wks can be functionally premature and develop RDS if the AFOD value is <0.40.

CONCLUSION

We conclude that no correlation between AFOD and mode of delivery, gestational age, and birth weight was observed and with AFOD <0.9 increased chances of respiratory distress, NICU admissions, and low APGAR score and increased perinatal morbidity and mortality. It was observed that babies born with AFOD values <0.40 are functionally premature irrespective of gestational age and are likely to develop RDS and may require mechanical ventilation. We hypothesize that each fetus has got its own maturity potential in terms of AFOD. Therefore, each feto-maternal unit is unique requiring an individualistic approach. AFOD estimation is cheap, easily available in any setting, and the results can be obtained within few minutes, and helps to make quick decisions when compared to L/S ratio estimation. As this is a small study, these results should be further evaluated by multicentric studies with larger sample size.

REFERENCES

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8. Samartha Ram H, Sandhya Ram S. Amniotic fluid optical density (AFOD) surge coincides with the onset of spontaneous term labor. Paper presented at 55th AICOG-2012. Varanasi, Book of abstracts 2014. p. 74.

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