Discussion
Main findings: The nuchal cord is considered as a physiological finding due to its high prevalence25. The incidence of NC is growing over a while.1, 2, 3, 4, 22, 23 and the perinatal outcome is uncertain, leaving behind increasing apprehension. The application of USG exhibit low sensitivity in diagnosing the nuchal cord.20,21 Our study shows similar results (Table 1). The factors responsible for this condition are unestablished. Few studies deny the association of NC with maternal age and parity.3,8,9,20 However, some studies exhibit significant relation of NC with male sex.6,9 The other aetiological factors like socioeconomic status and education level were not explored.
For the first time, in this study, we attempted to search in the maternal socioeconomic status, educational status apart from her age, parity, fetal gender. We observed that the socioeconomic factors played a significant role in NC (Fig.2). The lower SES patients had the highest incidence of NCB and the lowest incidence of NNCB. As the SES advanced to a middle and higher level, the incidence of NCB steeply decreased (***p). It was fascinating to follow no statistically significant difference in high school education groups (NCB versus NNCB). As the educational status advanced to intermediate, the incidence of NCB becomes significantly higher (Fig.3). The incidence of NCB was highest in graduates compared to all other groups (***p). We found that the NCB incidence is highest in the younger age group (up to 29 yrs) (***p). However, after 30 yrs there is no significant difference in NCB and NNCB. The result indicates that with the advancement of maternal age, there are decreased chances of an NC (Fig.1). We also observed that the nuchal cord was most common in the primigravidas (***p) (Fig.4). As parity advanced, the incidence of NCB declined. However, the incidence of NNCB was the maximum in the 2nd gravidas (**p). In the 3rd and 4th gravida groups, the incidence of NNCB was higher compared to NCB (*p). It was noted that NC is directly related to the male gender of the fetus (***p) (Fig 10).
The effect of NC on perinatal morbidity and mortality is studied with controversies. Few studies deny any perinatal morbidity associated with the NC, but it should be considered an ominous sign if associated with certain findings like intrauterine growth retardation and oligohydramnios.18 Some found that NC has adverse perinatal outcomes in their separate studies.4,11,12,13,14,19 Further, it was found that there was no APGAR score change due to the nuchal cord but increased fetal distress and fetal asphyxia.2, 3 The incidence of 1 min APGAR scores <7 was significantly higher in the NCB group, whereas that of 1 min APGAR ≥ 7 was significantly higher in the NNCB group (***p) (Fig.7). The need for O2 (***p) and NICU admission rate (*p) in the NCB group were significantly higher than those in the NNCB group (Fig.8). Interestingly, healthy babies’ incidence was higher in the NNCB group than the NCB group (**p). The study shows that the nuchal cord affects fetal outcomes, with significantly enhanced chances of low APGAR score (Fig.7) and the need for external support (Fig.8). We found that NC is associated with low fetal birth weight (***p) compared to NNCB (Fig.11).
The relationship between the amniotic fluid levels and the nuchal cord is scarcely known. It was observed that it might have a relation to acute onset polyhydramnios.7 We observed in our study that in the NNCB group, a maximum number of patients had AFI 11-12 cm, whereas those in the NCB group fell into AFI 8 – 9 cm (***p) (Fig.5). Most of the patients in NNCB had AFI ranging from 5 – 10.5 cm with none below AFI 4.5 cm and above 14 cm. However, many patients in the NCB group had AFI ≤ 4.5 cm and ≥ 14 cm (***p). The widespread distribution of the graph with a general shift towards the left in the NCB group versus the consolidated graph in the NNCB group shows the nuchal cord’s relationship to amniotic fluid volume (Fig.5). The nuchal cord’s occurrence in excessive amniotic fluid indicates that the excess fluid may be one of the etiological factors in the nuchal cord.
Similarly, its presence of lesser AFI (< 5 cm) group (***p) indicates that the nuchal cord is responsible for reduced liquor (Maybe due to disturbance of blood flow towards the fetus). The findings of liquor levels at the labour time were parallel to those of the AFI (Fig.5, Fig.6). We observed a significantly higher incidence of reduced liquor in the NCB group than the NNCB group. Whereas, in the NNCB group, the chances of having adequate liquor are more than having reduced liquor (***p). As per the excess liquor group is concerned, the NCB group incidence is significantly higher than that of the NNCB group. Overall, amniotic fluid and nuchal cord are significantly related to each other.
Strength and limitations: We observed 3 cases of short cord and 1 case of a true knot in the NNCB group. Simultaneously, there were no cases of either short cord or true knots in the NCB group. All these cord conditions and tightness of the nuchal cord could not be detected on USG prenatally. The tightness of the nuchal cord may play a vital role.11, 13, 14 Other cord conditions like short and stretched cord, true knot, highly coiled cord, compressed cord do affect the perinatal outcome. There was an important statement in a study saying that USG diagnosis will only be useful if we can 1. Diagnose a nuchal cord reliably, and 2. Predict which babies with nuchal cords are likely to have a problem.20 The tightness of the cord and other cord conditions are challenging to be detected with the present investigating methodologies. Thus, the question of diagnosing the problematic cord conditions persists. Hence, there is a definite need for a better diagnostic tool to assess the exact cord conditions, predicting perinatal morbidity if associated with them.
This study denotes that the nuchal cord incidence is high in theyoung age group, primigravida, higher educated, and low socioeconomic status . All of these situations are very stressful. By combining all these parameters, we could claim that the nuchal cord incidence is higher in patients with more stress. An extensive study needs to be conducted in this area.
Interpretation: The nuchal cord, with its aetiological factors and pathological outcomes, is no more a physiological condition. The proper management protocol is needed.