CONCLUSIONES Y RECOMENDACIONES.

xxxix Apgar score <7

in 5minutes 21 (36.8) 9 (15.8) 6.514 0.011 2.33 (1.71-4.65)

Neonatal intensive care unit admission

>24hours

12 (21.1) 6 (10.5) 2.375 0.123 2.00 (0.81-4.96)

Intrapartum fetal

death 1 (1.8) 0 (0.0) 0.000 1.000∞

Early neonatal death 5 (8.8) 1 (1.8) 1.583 0.208∞ 5.00 (0.60-41.47)

Birth weight <2.5kg 6 (10.5) 0 (0.0) 4.398 0.036∞

Normal outcome

25 (43.9) 41 (71.9) 9.212 0.002 2.00 (1.24-3.22)

B AFI: borderline AFI. N AFI: normal AFI. RR: relative risk. CI: confidence interval

∞: Yates’ continuity correction applied.

With respect to perinatal outcome as shown in Table 3, Intrapartum fetal distress (p = 0.035, RR = 2.29, CI = 1.02-8.13), Apgar score <7 in 5minutes (p = 0.011, RR = 2.33, CI = 1.71-4.65) and birthweight <2.5kg (p = 0.036) occurred more frequently in the borderline AFI group, this is statistically significant (p < 0.05) which disproves the null hypothesis of this study. Meconium stained liquor, Neonatal intensive care unit admission >24hours,

intrapartum fetal death and early neonatal death also occurred more frequently in the

borderline AFI group. However, this was not statistically significant (p > 0.05) and confirms the null hypothesis.

CHAPTER 6

xl gestational age, a comparison of the two groups for statistical significance was done to assess the effectiveness of the matching process. This showed that there was no statistically significant difference in the pattern of demographic variables such as maternal age, parity group, gestational age at study entry and gestational age at admission for delivery between the normal and borderline amniotic fluid index groups. This demonstrates that the impact of probable confounding variables had been reduced to the minimum. Biosocial variables are commonly seen as confounding in health research. While randomization is the best way of controlling for bias and confounders, matching has been shown to be very useful too when there are suspicions of likely confounders^49–52. The comparison of the exposed and non-exposed groups demonstrated its efficacy in this study.

The results of this study showed that mode of delivery such as spontaneous labour, induction of labour, assisted vaginal delivery, antepartum caesarean section, and intrapartum caesarean section were statistically significantly higher in the borderline AFI group.

Parturients with borderline AFI in this study were statistically significantly more likely to undergo induction of labour with a relative risk of 2.08. This was similar to findings from studies by Asgharnia et al¹, Gumus et al ²² and Choi ³⁰. Asgharnia and colleagues¹ (2013) compared women with normal and borderline AFI in the third trimester. Since women with borderline AFI are more likely to have induction of labour, there is an attendant increase in both maternal and neonatal morbidity and mortality. Induction of labour is associated with a higher risk of interventions such as caesarean sections, assisted vaginal delivery, ruptured uterus, postpartum haemorrhage as well as increased duration and cost of hospital care⁵³. Babies may also end up with morbidities such as neurological deficits due to birth asphyxia from fetal distress⁵⁴.

In this study, parturients with borderline AFI were thrice as likely to have assisted vaginal delivery (vacuum extraction or forceps delivery) compared to those with normal AFI.

xli This difference was statistically significant. This is in contrast to all previous findings on this theme. Gumus et al²² (2007) found no association between borderline AFI and assisted vaginal delivery. Theirs was a retrospective study involving women with singleton, uncomplicated, non-anomalous gestations, who underwent weekly monitoring of amniotic fluid index until delivery during the last trimester and who gave birth at their hospital.

Yaqoob et al³⁷ (2009), Mahapatro et al³⁹ (2013) and Wood et al³⁸ (2014) also did not establish significant association in their studies.

The implication of the statistical significance of assisted vaginal delivery in women with borderline AFI is that there might be an increased need for obstetric personnel at the delivery of these women, increased incidence of birth trauma (both maternal and fetal) and increased Neonatal intensive care services. Also of public health importance is a reduction in the caesarean section rate. It is known that a reduction in primary caesarean section reduces the overall caesarean section rate⁵⁵. Asides this, there is a negative attitude and strong aversion towards caesarean section amongst women in low-income countries including Nigeria as they prefer a vaginal delivery⁵⁶. Assisted vaginal delivery is also one of the critical functions of basic and comprehensive emergency obstetric recommended by WHO⁵⁷, and also reduces the overall cost of delivery.

In this study, parturients with borderline AFI were three times more likely to undergo caesarean delivery when compared to their normal AFI counterparts. This was statistically significant. Similar findings have been reported by Petrozella et al²⁸, Kwon et al ²⁹ and Jamal et al³³. However, the findings of Choi et al³⁰, Yaqoob et al³⁷, and Wood et al³⁸ are in contrast with the findings of this study. Differences may be due to the facts that these studies were retrospective studies. In addition, in the study by Choi et al³⁰, the ratio of normal to borderline AFI was 5:1.This may also partly explain the difference in findings. The increased likelihood of women with borderline AFI having caesarean delivery (both antepartum and

xlii intrapartum) increases the risks of complications such as anaesthetic risks, organ injury, need for blood transfusions, infections, as well as the risk of mortality⁵⁸.

A major finding of this study was that women with borderline AFI had a statistically significant, more than twice higher risk of intrapartum fetal distress and Apgar <7 in 5minutes . Parturients in the borderline AFI group were also statistically significantly more likely to have babies with birthweight <2.5kg. The finding in this study that the occurrence of intrapartum fetal distress was statistically significantly higher in the borderline AFI group is in keeping with that of previous studies by Gumus et al²² (2007) , Jeng et al³⁴ (1992) and Ulker and Ozdemir³⁶ (2011). Wood et al. ³⁸(2014) , Rutherford et al.²¹ (1987) and Banks et al²³ (1999) , in their studies however had contrary findings .They found no statistically significant difference in the rate of fetal intolerance of labour in pregnancies with a borderline AFI compared to those with a normal AFI. The study by Woods et al³⁸was a retrospective study with an approximately 5:1 ratio for normal to borderline AFI.

Considering the fact that fetal distress is more likely to occur in pregnancies with borderline AFI, the wide ratio between groups might be responsible for the absence of statistical significance. Intrapartum fetal distress occurring more amongst the babies whose mothers had borderline AFI increases the chances of the babies being born by assisted vaginal deliveries and also the attendant risks of birth traumas. They are also at a higher risk of respiratory morbidities such as transient tachypnoea of the new born and NICU admissions⁵⁹.

Apgar score of 0–3 at 5 minutes or more is regarded as a nonspecific sign of illness, which may be one of the first indications of encephalopathy⁵⁴. A low 5-minute Apgar score clearly confers an increased relative risk of cerebral palsy, reported to be as high as 20-fold to 100-fold over that of infants with a 5-minute Apgar score of 7–10⁶⁰. The difference in rates of

xliii occurrence of 5^th minute Apgar scores less than 7 between borderline and normal AFI groups in this study was statistically significant. Women with borderline AFI had babies who were two times more likely to have 5th minute Apgar scores less than 7. This finding was in keeping with previous studies of Kwon et al²⁸ (2006), Gumus et al²² (2007) and Asgharnia et al¹ (2015). However, the findings of a study by Banks and Miller are at variance with the findings of this study. It is likely that the fact that their study population included women with preterm and post term pregnancies would explain the different findings.

Birthweight may be influenced by several factors during pregnancy, one of which is liquor volume⁶¹. In this study, there was statistically significant difference between both study groups in terms of birthweight < 2.5kg. This is in line with the findings of several studies.1,22,23,28–30,39. This finding was however in contrast with the study by Baron et al (1995)²⁷ in a retrospective study involving patients with gestational age ≥ 26 weeks who had an intrapartum amniotic fluid index performed with subsequent delivery. Due to the fact that in Baron’s study, patients were recruited during labour, events during the antepartum period which may have had an effect on their findings could not be established.

In a similar vein, Jamal et al³³ (2008),looked at borderline amniotic fluid index and adverse perinatal outcome. They did not establish any statistically significant association between birthweight < 2.5kg and borderline amniotic fluid index. The fact that this was a retrospective study which compared 5 normal AFI parturients to 1 borderline AFI might explain the contrary finding. The clinical implication of the borderline AFI parturients having an increased relative risk of babies with birth weight <2.5 kg is that these babies have a greater risk of morbidity and mortality. They will require more expert care given by the paediatricians, increased hospital stay and cost, prone to neonatal infections, hypoglycaemia and othercomplications⁶².

xliv The strengths of this study include its prospective design, and matching of the possible confounding variables which increases the chance that the findings of the study are valid and generalizable to similar study population in Nigeria. The use of dedicated outcome personnel also minimises inter-observers’ error and ensured accurate outcome data for the variables of interest.

The study is not without limitations. The use of cardiotocography alone for the diagnosis of intrapartum hypoxia without the benefit of confirmatory modalities like fetal scalp blood sampling, fetal scalp lactate, fetal pulse oximetry and fetal electrocardiograph (ST- Analyzer or STAN) may have affected the rate of intervention in labour. However, since both arms of the study had CTG monitoring when indicated, the differential effect on any of the two arms is expected to be minimal. Also, the use of algorithms to assess and record what is normal, what requires more careful attention and what is considered abnormal requiring immediate delivery of the baby minimized inter and intra observer variations in CTG trace interpretation ⁴⁵⁴⁶. Another limitation encountered is bias introduced by intra observer error with regards to sonographic determination of AFI. Significant intra observer variability is known to exist in the sonographic evaluation of the gravid uterus⁴⁷. This has been shown to be the case even in the best of hands, as ultrasound evaluation is highly operator and machine dependent. However, the impact this might have on the study is likely minimal as the investigator was part of the scanning of all the patients studied.

Consequent upon national industrial strike actions, some of the study participants were lost to follow up. However, this was overcome by recruitment of fresh participants and extension of the study period.

CONCLUSION

In this study, more women with normal AFI had spontaneous labour. There was a

xlv statistically significantly higher difference in women with borderline AFI with respect to modes of delivery such as spontaneous labour, induction of labour, assisted vaginal delivery and caesarean delivery. This was in addition to perinatal outcomes such as intrapartum fetal distress, Apgar score < 7 in 5 minutes and birthweight < 2.5kg.

However , this study did not show any statistically significant difference between proportions of the perinatal outcome measures such as meconium stained liquor, Neonatal intensive care unit admission >24hours, Intra partum fetal death and early neonatal death.

RECOMMENDATION

xlvi 1. The available evidence from this study suggests the increased risk of adverse pregnancy outcomes in low risk Nigerian women with borderline AFI such as induction of labour, assisted vaginal delivery, caesarean section, intrapartum fetal distress, Apgar score < 7 in 5 minutes and birthweight < 2.5kg. As such, due to the lack of a definite care protocol and specific decision about delivery for these patients, there is thus a need for the establishment and formulation of protocols on the management of these patients with borderline AFI whereby closer observation and increased antepartum surveillance be instituted in order to avoid adverse perinatal outcome.

2. Based on the fact that the prospective cohort design of this study which allowed for control of possible confounding variables was utilized, it is most likely that the findings were representative of those in the general population. However, randomized controlled studies may be helpful in further confirming the findings.

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APPENDIX 1

INFORMATION SHEET