Umbilical Cord Blood Gas Analysis, Obstetric Performance and Perinatal Outcome

To analyze if umbilical artery pH (pHua) ≤7.00 and umbilical artery blood deficit (BDua) ≥12.00 mmol/L are good predictors of adverse neonatal outcomes.

Methods

This was an observational, longitudinal and retrospective cohort study, conducted at the department of obstetrics and gynecology of Centro Hospitalar Tondela Viseu between September 2013 and September 2015. Total cohort and subgroup analysis were performed: group A-women with umbilical cord blood gas analysis (UCBGA) performed for non-reassuring fetal cardiotocographic patterns, placental abruption, or shoulder dystocia; and group B-all the others. Assays were made with the software SPSS for Windows, Versions 20.0 and 21.0 (IBM Corp., Armonk, NY, USA).

Results

A total of 428 UCBGAs met the inclusion criteria. The group analysis revealed an association between group A and pHua ≤7.00, as well as between BDua ≥12.00 mmol/L and 1st minute Apgar score ≤4 (p = 0.011). After the application of the logistic regression models in the total cohort analysis, pHua ≤7.00 had an impact in the occurrence of acute neonatal hypoxia (odds ratio [OR]: 6.71; 95% confidence interval [CI]: 1.21-37.06; p = 0.029); multiparous women had a higher risk of delivering a newborn with first minute Apgar score ≤4 and acute neonatal hypoxia (OR: 5.38; 95% CI: 1.35-21.43; p = 0.017; and OR: 2.66; 95% CI: 1.03-6.89, p = 0.043, respectively); women who had urologic problems during pregnancy had a higher risk of delivering a newborn with 5th minute Apgar score ≤7 (OR: 15.17; 95% CI: 1.29-177.99; p = 0.030); and shoulder dystocia represented a 15 times higher risk of acute neonatal hypoxia (OR: 14.82; 95% CI: 2.20-99.60; p = 0.006).

Conclusion

The pHua and the BDua are predictors of adverse neonatal outcome, and UCBGA is a useful tool for screening newborns at risk. Universal UCBGA should be considered for all deliveries, as it is an accurate screening test for neonatal hypoxia.

Keywords:
Umbilical Cord Blood Gas Analysis; delivery; morbidity; neonatology

Variables	Total cohort		Group A		Group B
	n	%	n	%	n	%	p-value
Maternal age (years old)							0.957
≤ 19	10	2.3	1	0.6	9	3.6
20–24	36	8.4	16	9.1	20	7.9
25–29	117	27.3	52	29.7	65	25.7
30–34	158	36.9	62	35.4	96	37.9
35–37	57	13.3	27	15.4	30	11.9
≥ 38	50	11.7	17	9.7	33	13.0
Parity							0.092
Nulliparous	291	68.0	111	63.4	180	71.1
Multiparous	137	21.0	64	36.6	73	28.9
Insulin treated gestational diabetes							0.714
No	409	95.6	168	96.0	241	95.3
Yes	19	4.4	7	4.0	12	4.7
Non-insulin treated gestational diabetes							1.000
No	419	97.9	171	97.7	248	98.0
Yes	9	2.1	4	2.3	5	2.0
Gestational hypertension							0.481
No	420	98.1	173	97.7	247	97.6
Yes	8	1.9	2	2.3	6	2.4
Urologic problems during pregnancy							0.164
No	423	98.8	171	97.7	252	99.6
Yes	5	1.2	4	2.3	1	0.4
Oligohydramnios							0.481
No	420	98.1	173	98.9	247	97.6
Yes	8	1.9	2	1.1	6	2.4
Gestational age at birth (gestational weeks)							0.667
37–38	75	17.5	29	16.6	46	18.2
≥ 39	353	82.5	146	83.4	207	81.8
Delivery							0.000
Normal vaginal	25	5.8	9	5.1	16	6.3
Vacuum	239	55.8	80	55.8	159	62.8
Forceps	30	7.0	9	5.1	21	8.3
Caesarean section	134	31.3	175	44.0	57	22.5
UCBGA motive							0.000
Control	14	3.3	0	0.0	14	5.5
Assisted reproductive technology	1	0.2	0	0.0	1	0.4
Small for gestational age newborn	1	0.2	0	0.0	1	0.4
Instrumental delivery	235	54.9	0	0.0	235	92.9
Non-reassuring fetal CTG pattern	171	40.0	171	97.7	0	0.0
Placental abruption	4	0.9	4	2.3	0	0.0
Shoulder dystocia	2	0.5	0	0.0	2	0.8
Gender							0.015
Female	184	43.0	63	36.0	121	47.8
Male	244	57.0	112	64.0	132	52.2
Birthweight (grams)							0.013
< 4,000	415	97.0	174	99.4	241	95.3
≥ 4,000	13	3.0	1	0.6	12	4.7
Total	428	100.0	175	100.0	253	100.0

Variables	Total cohort		Group A		Group B
	n	%	n	%	n	%	p-value
pH_ua							0.002
≤ 7.00	17	4.0	13	7.4	4	1.6
> 7.00	411	96.0	162	92.6	249	98.4
BD_ua (mmol/L)							0.721
≥ 12.00	8	1.9	4	2.3	4	1.6
< 12.00	420	98.1	171	97.7	249	98.4

Variables	Total cohort		Group A		Group B
	n	%	n	%	n	%	p-value
Adverse neonatal outcome							0.065
No	379	88.6	149	85.1	230	90.9
Yes	49	11.4	26	14.9	23	9.1
1′AS							0.078
≤ 4	416	97.2	8	4.6	4	1.6
> 4	12	2.8	167	95.4	249	98.4
5′ AS							0.020
≤ 7	421	98.4	6	3.4	1	0.4
> 7	7	1.6	169	96.6	252	99.6
ANH							0.189
No	408	95.3	164	93.7	244	96.4
Yes	20	4.7	11	6.3	9	3.6
HIE							1.000
No	427	99.8	175	100.0	252	99.6
Yes	1	0.2	0	0.0	1	0.4
Neonatal seizures							1.000
No	426	99.5	174	99.4	252	99.6
Yes	2	0.5	1	0.6	1	0.4
RDS I							0.057
No	417	97.4	167	95.4	250	98.8
Yes	11	2.6	8	4.6	3	1.2
RDS II							0.203
No	412	96.3	9	5.1	246	97.2
Yes	16	3.7	166	94.9	7	2.8
Meconium aspiration syndrome
No	424	99.1	173	98.9	251	99.2	1.000
Yes	4	0.9	2	1.1	2	0.8	1.000
Neonatal bradycardia
No	423	98.8	174	99.4	249	98.4	0.653
Yes	5	1.2	1	0.6	4	1.6	0.653
Neonatal sepsis							1.000
No	424	99.1	173	98.9	251	99.2
Yes	4	0.9	2	1.1	2	0.8

Variables	Total cohort			Group A			Group B
	OR	95% CI	p-value	OR	95% CI	p-value	OR	95% CI	p-value
pH_ua ≤7.00
1′AS ≤4	9.57	2.33–39.25	0.009	4.73	0.85–26.22	0.111	27.33	2.17–344.29	0.062
5′AS ≤7	10.83	1.94–60.40	0.028	2.62	0.28–24.23	0.375	n.a.	n.a.	0.016
ANH	7.60	2.23–25.91	0.006	3.09	0.59–16.09	0.191	34.57	4.24–282.06	0.007
Neonatal seizures	n.a.	n.a.	0.439	n.a.	n.a.	1.000	n.a.	n.a.	0.242
RDS I	2.51	0.30–20.79	0.363	1.85	0.21–16.26	0.468	n.a.	n.a.	1.000
RDS II	3.78	0.79–18.15	0.128	4.03	0.75–21.74	0.136	n.a.	n.a.	1.000
Meconium aspiration syndrome	n.a.	n.a.	1.000	n.a.	n.a.	1.000	n.a.	n.a.	1.000
Neonatal bradycardia	4.17	0.46–37.65	0.210	n.a.	n.a.	1.000	3.92	0.40–38.18	0.322
Neonatal sepsis	3.12	0.32–30.19	3.120	n.a.	n.a.	0.507	1.28	0.08–20.72	1.000
BD_ua ≥12.00 mmol/L
1′AS ≤4	27.40	5.66–132.54	0.001	27.50	3.29–229.68	0.011	27.33	2.17–344.29	0.062
5′AS ≤7	9.86	1.04–93.05	0.125	n.a.	n.a.	0.016	n.a.	n.a.	1.000
ANH	7.44	1.40–39.49	0.049	5.37	0.51–56.36	0.230	10.04	0.94–107.45	0.136
Neonatal seizures	n.a.	n.a.	1.000	n.a.	n.a.	1.000	n.a.	n.a.	1.000
RDS I	n.a.	n.a.	1.000	n.a.	n.a.	1.000	n.a.	n.a.	1.000
RDS II	3.86	0.45–33–37	0.265	6.79	0.63–71.79	0.192	n.a.	n.a.	1.000
Meconium aspiration syndrome	n.a.	n.a.	1.000	n.a.	n.a.	1.000	n.a.	n.a.	1.000
Neonatal bradycardia	n.a.	n.a.	1.000	n.a.	n.a.	1.000	n.a.	n.a.	1.000
Neonatal sepsis	n.a.	n.a.	1.000	n.a.	n.a.	1.000	n.a.	n.a.	1.000

Variables	1′AS ≤ 4			5′AS ≤ 7			ANH
	OR	95% CI	p-value	OR	95% CI	p-value	OR	95% CI	p-value
Study group	2.98	0.88–10.06	0.078	8.95	1.97–74.98	0.020	1.82	0.74–4.49	0.244
Maternal age	1.24	0.37–4.18	1.000	0.82	0.18–3.70	1.000	1.15	0.45–2.94	0.771
Parity	4.45	1.32–15.04	0.022	5.47	1.05–28.58	0.037	2.74	1.11–6.77	0.024
Insulin treated gestational diabetes	2.010	0.246	0.424	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.
Non-insulin treated gestational diabetes	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.
Gestational hypertension	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.
Urologic problems during pregnancy	9.36	0.97–90.78	0.133	17.36	1.68–179.44	0.080	5.32	057–49.89	0.214
Oligohydramnios	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.
Gestational age at birth	1.06	0.23–4.96	1.000	n.a.	n.a.	n.a.	0.62	0.22–1.77	0.368
Vacuum delivery	0.39	0.11–1.30	0.111	1.06	0.23–4.77	1.000	0.63	0.26–1.56	0.317
Forceps delivery	2.77	0.58–13.27	0.202	2.25	0.26–19.35	0.401	2.49	0.69–9.03	0.157
Cesarean section	2.25	0.71–7.11	0.205	0.88	0.17–4.57	1.000	1.19	0.46–3.06	0.715
Newborn's gender	0.43	0.12–1.62	0.202	0.53	0.10–2.74	0.704	0.70	0.28–1.80	0.460
Birthweight	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.
Shoulder dystocia	9.36	0.97–90.78	0.133	n.a.	n.a.	n.a.	15.00	2.36–95.43	0.019
Neonatal sepsis	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.	n.a.

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[1] Address for correspondence
Cátia Sofia Ferreira, MD, Serviço de Ginecologia e Obstetrícia, Centro Hospitalar Tondela-Viseu, Avenida Rei D. Duarte, 3504-509, Viseu, Portugal (e-mail: csf0301@gmail.com).