Introduction

Administration of maternal O₂ is a commonly performed intrauterine of pregnant women as a resuscitation technique, where more than 50% of births are given additional oxygen. Maternal O₂ administration may range from minutes to hours, that might reach 78% of the duration of labor.

It was reported that oxygen supplementation was used to improve fetal acid-base metabolism or suspicious fetal heart monitoring patterns.

While the American College of Obstetricians and Gynecologists (ACOG) indicated that there was no evidence for maternal oxygen.

Another study reported that O₂ administration improves category II fetal heart tracings (FHTs), that may be correlated with fetal hypoxemia and acidemia leading to maternal hyperoxygenation and promoted oxygen transfer from placenta to the fetal circulation.

 

Patients and Methods

Study design: A retrospective study.

Settings: Obstetrics and Gynecology department, King Fahad Hospital,Al-Bahah, Saudi Arabia.

Period: Three months

Study population: Saudi pregnant women

Participant's age: 18 and above

Inclusion criteria: Saudi pregnant women who resident in Al-Bahahand attending Obstetrics and Gynecology department at King Fahad Hospital, who received intrapartum maternal oxygen.

Exclusion criteria: Participants who didn’t meet the inclusion criteria

Sample technique: A random sampling technique.

Sample size: A convenient sample size was collected from Obstetrics and Gynecology department at King Fahad Hospital, and who received intrapartum maternal oxygen.

 

Study Tools:

A retrospective study was conducted among Saudi pregnant women who aged ? 18years old, resident in Al-Bahah and attending Obstetrics and Gynecology department at King Fahad Hospital, and who received intrapartum maternal oxygen. After the approval of the institutional review board (IRB), data regarding oxygen flow rate, duration of exposure, outcome of the infants, and fetal heart rate was collected from patients’ medical records.

Additionally, other demographic data for each woman was collected from the medical records of patients (age, marital status, educational level, employment status)

 

Ethical Consideration:

Ethical approval was obtained from the institutional review board (IRB) before data collection. The privacy and confidentiality of the data and study results were secured by restricting unauthorized access.

 

Statistical Analysis:

Data was analyzed using IBM SPSS, version 22. A P value lower than 0.05 was considered significant. Numbers and percentages were used to presents all categorical variables.

 

Results

There were 192 women included in our final analysis; all patients were admitted to the hospital in an active state of delivery and were put on high oxygen flow during the intrapartum period. Mothers had a mean age of 31.4 ± 5.6 years old. The characteristics of mothers are shown in table 1.

The obstetric history of the mothers and qualitative demographics are shown in table 2; the obstetric history of the females includes gravid, parity, mode of delivery, and APGAR 5 and 10, whereas the educational level and medical conditions belong to the qualitative demographics. The largest proportion of females (29.2%) reported one parity, spontaneous vaginal delivery (54.2%), and suffer no medical conditions (45.8%).

 The correlations between the intrapartum oxygenation amount and the outcome of the fetus, including the mode of delivery, APGAR 5 and 10, were investigated (table 3,4). The mean amount of oxygen has significantly influenced the mode of delivery (P?0.0001) and APGAR 5(P=0.001). Significant positive correlations were found between the mean of oxygen amount and each of gestational age, weight o the fetus, and pH (table 4).

 

Regarding the duration of oxygen supply, there were significant correlations between the duration of supplying oxygen and mode of delivery, APGAR5 and 10 (table5). Also, there were no significant correlations between the duration of oxygenation and each of gestational age, the weight of the fetus, and pH (table 6).

 

Discussion

Resuscitation of the newborn is the fundamental approach in the delivery room to ensure maintenance and quality of life ,More than one million neonates annually need resuscitation. It was indicated that 100% oxygen supplementation during resuscitation might be harmful due to oxygen-free radicals that affect the pathogenesis of several disorders of the newborn. It was found that 21% oxygen was associated with a lower rate of neonatal mortality. The analysis of Umbilical cord blood gas is an indicator for fetal acid-base balance and fetal response to birth stress.[ In the current study, we investigated the oxygenation characteristics and their impact on the mother and the fetal outcome.

 In this study, the oxygen amount was assessed in a liter, and the oxygen duration of exposure was assessed in minutes; the mean oxygen amount was 7.45 liters, whereas the duration of oxygen supplying was 30.32 minutes. Regarding the amount of oxygen, the mean of the amount is significantly associated with the mode of delivery and APGAR score 5. The highest mean value of oxygen amount was significantly associated with spontaneous delivery (7.3liters) and a higher APGAR 5 score. Regarding the neonatal outcomes, the mean amount of oxygen was significantly and positively associated with gestational age, the weight of the fetus, and the pH. This means that increasing the amount of oxygen is significantly associated with increased pH. The duration of oxygen also was associated with the mode of delivery, APGAR scores 5 and 10. However, the longer duration of oxygen was associated with lower segment cesarean section and lower APGAR score. On the other hand, the duration of oxygen supply had no impact on neonatal outcomes.

Uslu et al.[20] demonstrated that there was a significant correlation between the level of SpO2 and the Umbilical cord arterial pH values. Another study was conducted on two groups of mothers to assess the effect of administration of maternal low flow oxygen during the second stage of labor on umbilical cord artery pH; one group received a flow rate of 2 L/min, and the other one received a sham supplementation by nasal cannula. The study revealed that the Umbilical cord pH wasn’t varied between the two groups.[14] Another study reported that oxygenation during the second stage of labor was significantly harmful.[15]

A randomized controlled trial conducted on 86 females demonstrated that the group of females who received oxygen showed a considerably lower pH of the Umbilical cord of less than 7.2 compared to the control group.[16]

In our study, the amount of oxygen supply had a significant positive association with the pH; the pH is increasing with increasing the amount of oxygen. However, the oxygen supply can be limited to a lower amount to avoid any increase in the pH. In one study, it was found that the threshold pH for adverse neurological outcomes was7.10, and the ideal pH of the cord was ranging between 7.26-7.30. Above 7.00, however, neonatal acidaemia is weakly associated with adverse outcomes.[26]

 

Conclusion

Oxygenation amount was associated with the mode of delivery and increased with gestational age and weight of the fetus; it was also associated with the pH. On the other hand, the duration of oxygenation affects the mode of delivery and APGAR but had no significant impact on the fetus outcomes such as pH. It seems that the amount of oxygen had significant positive outcomes for the mothers, but it can affect the level of pH of the neonates, whereas the long duration had non-favorable maternal outcomes with no impact on the fetal outcomes.

 

Table 1 descriptive statistics of the included mothers

Variables	Mean	SD	Min	Max
Gestational age	37.83	2.36	29.00	41.00
Oxygen amount in liters	7.45	1.82	5.00	10.00
Duration in minutes	30.32	12.07	10.00	60.00
Weight of the baby	2.94	0.51	1.12	3.75
PH	7.24	0.07	7.10	7.40

Table 2: showing the obstetric history of the included pregnant ladies

Varriables		Count	Column N %
Gravid	1	22	11.5%
	2	35	18.2%
	3	55	28.6%
	4	15	7.8%
	5	12	6. %
	6	33	17.2%
	8	10	5.2%
	9	10	5.2%
Parity	0	22	11.5%
	1	56	29.2%
	2	77	40.1%
	3	4	2.1%
	4	13	6.8%
	5	10	5.2%
	8	10	5.2%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9	40	20.8%
APGER 10	8	24	12.5%
	9	66	34.4%
	10	102	53.1%

 

Table 3 correlations between fetus outcome and intrapartum oxygenation

 

Table 4 showing correlations between fetus outcome and oxygenation amount

Variable	Spearman correlation coefficient	P-value
Gestational age	0.39	<0.0001
Weight of the fetus	0.28	<0.0001
PH	0.43	<0.0001

Table 5 correlations between fetus outcome and intrapartum oxygenation duration

Variables		oxygen amount in liters		P-value
		Mean	Standard Deviation
Mode of delivery	Assisted breech	15.0	0	0.016
	LSCS	33.7	13.0
	SVD	27.6	10.5
APGER 5	7	36.5	12.1	<0.000   1
	8	25.8	11.0
	9	29.2	9.7
APGER 10	8	35.8	5.9	<0.000   1
	9	27.9	9.9
	10	30.6	13.9
Kruskal Wallis test

Table 6 showing correlations between fetus outcome and duration of oxygenation

Variable	Spearman correlation coefficient	P-value
Gestational age	0.13	0.054
Weight of the fetus	0.03	0.63
PH	0.013	0.85

 

References

1. Hamel MS, Anderson BL, Rouse DJ. Oxygen for intrauterine resuscitation: of unproved benefit and potentially harmful. Am J Obstet Gynecol. 2017; 211(2):124–7.

2. Ankumah NE, Blackwell SC, Alrais MA, Amro FH, Wiley RL, Heale P, et al. Liberal versus indicated maternal oxygen supplementation in labor: a before-and-after trial. Am J Perinatol 2018;35:1057–64.

3. American College of Obstetricians and Gynecologists. Practice bulletin no. 116: management of intrapartum fetal heart rate tracings. Obstet Gynecol. 2010;116(5):1232–40.

4. Cahill AG, Roehl KA, Odibo AO, Macones GA. Association and prediction of neonatal acidemia. Am J Obstet Gynecol 2012;207:206.e1–8

5. Elliott C, Warrick PA, Graham E, Hamilton EF. Graded classification of fetal heart rate tracings: association with neonatal metabolic acidosis and neurologic morbidity. Am J Obstet Gynecol 2010;202:258.e1–8.

6. Khaw KS, Wang CC, Ngan Kee WD, Pang CP, Rogers MS. Effects of high inspired oxygen fraction during elective caesarean section under spinal anaesthesia on maternal and fetal oxygenation and lipid peroxidation. Br J Anaesth 2002;88:18–23.

7. Simpson KR, James DC. Efficacy of intrauterine resuscitation techniques in improving fetal oxygen status during labor. Obstet Gynecol 2005;105:1362–8.

8. Hamel MS, Anderson BL, Rouse DJ. Oxygen for intrauterine resuscitation: of unproved benefit and potentially harmful. Am J Obstet Gynecol 2014;211:124–7

9. Watkins VY, Martin S, Macones GA, Tuuli MG, Cahill AG, Raghuraman N. The duration of intrapartum supplemental oxygen administration and umbilical cord oxygen content. American Journal of Obstetrics and Gynecology;2020.  doi:10.1016/j.ajog.2020.05.056.