Analysis of risk factors and complications of neonatal infection in 500 pregnant women with premature rupture of membranes

doi:10.21203/rs.3.rs-5280140/v1

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Analysis of risk factors and complications of neonatal infection in 500 pregnant women with premature rupture of membranes

https://doi.org/10.21203/rs.3.rs-5280140/v1

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Objective

Analyze the risk factors and complications of neonatal infection in 500 pregnant women with premature rupture of membranes(PROM), providing guidance for early prevention and timely treatment in clinical practice.

Methods

This retrospective study included 500 pregnant women randomly selected between October 2023 and October 2024, who were admitted to the obstetrics department of Wenzhou People's Hospital,Zhejiang Province, China, at 37-40 weeks of pregnancy due to PROM.Based on the infection status of newborns, the participants were divided into an infected group(77 cases) and an uninfected group(423 cases).The differences between the two groups were compared,and the risk factors and complications of neonatal infections were evaluated and analyzed.

Results

Neonatal infection was used as the dependent variable,while the duration of PROM, length of the first stage, length of the second stage, nulliparity, placental inflammation,fetal tachocardia, prenatal fever, amniotic fluid contamination,and group B streptococcus (GBS) colonization were used as independent variables. The results indicated that the duration of PROM, length of the first stage,length of the second stage,placental inflammation,fetal tachocardia, prenatal fever, amniotic fluid contamination,and GBS colonization wereindependent risk factors for neonatal infections (p<0.05).In this study, the neonatal infection rate was 15.4%, including 19 cases of pneumonia (24.6%), 8 cases of respiratory distress syndrome (10.4%), 10 cases of respiratory failure (13.0%), and 40 cases of early-onset neonatal infection (52.0%). Among the 77 cases of neonatal infections, 11 cases (14.3%) were severe infections.

Conclusion: Pregnant women with PROM face a higher risk of neonatal infection and severe neonatal infection, especially when associated with certain risk factors. In clinical practice, it is crucial to closely monitorfull-term pregnant women with PROM, improve the management of PROM, actively administer antibiotics to prevent infection, and terminate pregnancy promptly to minimize neonatal risks.These measures can help prevent and reduce the occurrence of neonatal infections, including severe cases.

Premature rupture of membranes

Neonatal infection

Pregnant women

Risk factors

complication

During pregnancy, the level of estrogen in pregnant women increases, and the glycogen in vaginal epithelial cells continues to accumulate, causing the vaginal environment to become overly acidic which creates favorable conditions for microbial growth.This leads to a increased susceptiblity to infection^[1].Additionally,the increase in progesterone further affects the endocrine system of pregnant women, impairing cellular immune function and making reproductive tract infections more likely^[2–3].PROM refers to the rupture of the amniotic membranes before the onset of labor. When PROM occurs, the body's resistance decreases, significantly increasing the risk of maternal, fetal, and neonatal complications, with infection being the primary concern^[4].For the mother, PROM-related infections can manifest as intrauterine infections, pregnancy complications, and postpartum endometritis. For newborns, PROM may lead to early infections, including sepsis or septic shock^[5].The infections caused by PROM often lack specific clinical sysptoms, resulting in delayed diagnoses, prolonged disease courses, worsening of the conditions, and adverse outcomes for both mothers and newborns ^[6–7]. Neonatal infections are most commonly observed within the first 72 hours after birth, with bacterial infections being the most prevalent. The incidence of neonatal infections is approximately 10%, and they are a major cause of increased neonatal morbidity and mortality rates^[8]. The causes of neonatal infection in pregnant women with PROM are multifaceted, and no unified conclusion has been reached. Further research is required to clarify these causes. Therefore, this study investigates the risk factors for neonatal infections in pregnant women with PROM and analyzes the associated complications, providing a reference for the prevention and treatment of neonatal infections in clinical practice.

1.1 Study design

With the approval of the hospital ethics committee, we conducted a retrospective case-control study involving 500 pregnant women with premature rupture of membranes (PROM) who were admitted to the obstetrics department of Wenzhou People's Hospital, Zhejiang Province, China, between October 2023 and October 2024. All data were obtained from the patients' medical records. Based on the presence or absence of neonatal infections, the women were categorized into an infected group (77 cases) and an uninfected group (423 cases).

Inclusion criteria: Single live birth, gestational age between 37-40 weeks, regular prenatal check ups, diagnosis of PROM, and informed patient consent.

Exclusion criteria: Severe pregnancy complications, serious liver, kidney, or other organ diseases, pregnancy terminated via cesarean section, and cases that did not meet the diagnosis of PROM.

1.2 Definition

The definition of PROM is the leakage of amniotic fluid through the vagina, confirmed by a pH test of vaginal fluid showing alkalinity. False positives due to blood, bacterial vaginosis, or other factors must be ruled out^[4].

Group B Streptococcus (GBS) is a conditional pathogen that mainly colonized the human urinary and reproductive tract in the lower gastrointestinal tract. The American College of Obstetricians and Gynecologists (ACOG) recommends conducting GBS screening for all pregnant women aged 35-37 weeks, with those who test positive are defined as GBS colonization^[9-10].

1.3 Collection of clinical data

We gathered basic demographic and clinical information on all pregnant women and their newborns, including maternal age, pre-delivery BMI, gestational age, newborn birth weight, Apgar 1-minute score, prenatal white blood cell count(WBC), and C-reactive protein(CRP) levels. We also recorded the duration of PROM, length of the first stage, length of the second stage, nulliparity, placental inflammation, fetal tachycardia, prenatal fever, amniotic fluid contamination, GBS colonization in the reproductive tract, incidence of neonatal infections, and associated complications. All data were subjected to statistical analysis.

1.4 Statistical analysis

Statistical analysis was performed using SPSS 27.0 software. Quantitative data were compared between the two groups using the t-test or non-parametric tests, while categorical data were analyzed using χ2 tests. Binary logistic regression analysis was used to identify risk factors for neonatal infections. p<0.05 was considered statistically significant.

2.1 Comparison of basic information between Two Groups

A total of 500 eligible pregnant women were categorized into an infected group (77 cases) and an uninfected group (423 cases) based on the occurrence of early neonatal infection.The average age of the infected group was 28.12 years (SD ± 4.44 years), while the average age of the uninfected group was 28.76 years (SD ± 4.08 years). The pre-delivery BMI of the infected group was 26.34 Kg/m² (SD ± 3.07 Kg/m²), and that of the uninfected group was 26.47 Kg/m² (SD ± 3.18 Kg/m²). The GA of the infected group was 38.88 weeks (SD ± 1.01 weeks), and that of the uninfected group was 38.77 weeks (SD ± 0.96 weeks). The BW of the infected group was 3256.45 g (SD ± 352.80 g), and taht of the uninfected group was 3227.95 g(SD ± 331.48 g). The Apgar score at 1 minute for the infected group was 9.84 (SD ± 0.56), and for the uninfected group, it was 9.97 (SD ± 0.22). There were no statistically significant differences between the two groups (p > 0.05) (Table 1).

The levels of prenatal WBC and CRP in the infected group were higher than those in the uninfected group. The median prenatal WBC level in the infected group was 11.00 × 10⁹/L (IQR 9.00–13.00× 10⁹/L), while in the uninfected group, it was 8.70 × 10⁹/L (IQR 7.35–10.05× 10⁹/L). The median prenatal CRP level in the infected group was 6.00 mg/L (IQR 2.60–11.00 mg/L), and in the uninfected group, it was 2.30 mg/L (IQR 1.20–4.30 mg/L). These differences were statistically significant (p < 0.001).

2.2 Univariate comparison of risk factors for neonatal infection between Two Groups

Univariate analysis revealed that the duration of PROM, length of the first stage, length of the second stage, nulliparity, placental inflammation, fetal tachycardia, prenatal fever, amniotic fluid contamination, and GBS colonization in the reproductive tract were associated with neonatal infection. The incidence of these fators was higher in the infected group than in the uninfected group, and the differences were statistically significant (Table 2).

2.3 Logistic analysis of risk factors for neonatal infection between Two Groups

Using neonatal infection as the dependent variable, and the duration of PROM, length of the first stage, length of the second stage,nulliparity, placental inflammation, fetal tachycardia, prenatal fever, amniotic fluid contamination, and reproductive tract GBS colonization as independent variables, the analysis revealed that the duration of PROM, length of the first stage, length of the second stage, placental inflammation, fetal thyroid, prenatal fever, amniotic fluid contamination, and GBS colonization were all independent risk factors for neonatal infection(p < 0.05). The corresponding OR values were 0.90, 1.18, 5.91, 20.11, 2.59, 7.03, 8.13, and 5.19, respectively (Fig. 1).

2.4 Analysis of neonatal complications

Among the 500 pregnant women with premature rupture of membranes, 77 cases of neonatal infections were identified, resulting in a neonatal infection rate of 15.4%. Of these, 19 cases (24.6%) were pneumonia, 8 cases (10.4%) were respiratory distress syndrome, 10 cases (13.0%) were respiratory failure, 40 cases (52.0%) were early-onset neonatal infections, and 11 cases (14.3%) were severe infections.

Table 1

Maternal and neonatal characteristics of the study population
	Newborn infection (n = 77)	Non-Newborn infection (n = 423)	t/Z	P
Age,years	28.12 ± 4.44	28.76 ± 4.08	-1.25	0.212
BMI before delivery,Kg/m²	26.34 ± 3.07	26.47 ± 3.18	-0.34	0.733
Gestational age,weeks	38.88 ± 1.01	38.77 ± 0.96	0.92	0.359
Birth weight, g	3256.45 ± 352.80	3227.95 ± 331.48	0.79	0.428
Apgar at 1min,scores	9.84 ± 0.56	9.97 ± 0.22	-1.99	0.050
WBC before birth,10⁹/L	11.00 (9.00, 13.00)	8.70 (7.35, 10.05)	6.15	< .001
CRP before birth,mg/L	6.00 (2.60, 11.00)	2.30 (1.20, 4.30)	7.00	< .001

WBC: white blood cells,CRP: C-reactive protein.

Table 2

Univariate analysis of risk factors for early infection in newborns
Variables	Newborn infection (n = 77)	Non-Newborn infection (n = 423)	t/χ²	P
Duration of PROM,h	11.69 ± 6.22	9.91 ± 6.78	2.50	0.013
Length of the first stage,h	9.85 ± 4.99	5.21 ± 3.00	7.90	< .001
Length of the second stage,h	1.63 ± 0.78	0.65 ± 0.59	10.53	< .001
Nulliparity,n(%)			5.96	0.015
N	21 (27.27)	178 (42.08)
Y	56 (72.73)	245 (57.92)
Placental inflammation, n(%)			104.68	< .001
N	5 (6.49)	291 (68.79)
Y	72 (93.51)	132 (31.21)
Fetal tachycardia, n(%)			66.61	< .001
N	34 (44.16)	361 (85.34)
Y	43 (55.84)	62 (14.66)
Prenatal fever, n(%)			45.93	< .001
N	56 (72.73)	404 (95.51)
Y	21 (27.27)	19 (4.49)
Amniotic fluid contamination, n(%)			34.31	< .001
N	62 (80.52)	412 (97.40)
Y	15 (19.48)	11 (2.60)
GBS colonization, n(%)			62.10	< .001
N	56 (72.73)	411 (97.16)
Y	21 (27.27)	12 (2.84)

PROM:premature rupture of membranes,GBS:Group B streptococcus.

The fetal membrane is a flexible structure that encloses the fetus within the uterine cavity, storing amniotic fluid and adapting to the continuous development of the fetus, thus providing a favorable spatial environment for fetal growth. As such, the fetal membrane plays a protective role for the fetus ^[11].Several factors can contribute to the premature rupture of membranes, including reproductive tract infections, uneven stress on the membranes, external forces, and potentially a combination of these factors ^[12]. Among these, reproductive tract infections are considered a primary cause of poor pregnancy outcomes, such as premature rupture of membranes, preterm birth, and postpartum infections, and they are closely linked to PROM ^[13–14].In the later stages of pregnancy, a large number of microorganisms colonize the vaginal tract of pregnant women. These microorganisms maintain a dynamic balance, interacting and constraining each other to preserve the equilibrium of the vaginal microbiota ^[15].When PROM occurs, the continuous leakage of amniotic fluid can disrupt the normal bacterial community in the vagina, weakening the immune resistance of pregnant women and disturbing the microecological balance of the vaginal environment. This disturbance can increase the survival and proliferation of pathogenic bacteria. Given the close connection between the vagina and the amniotic cavity, these proliferating pathogens can easily lead to uterine infections, potentially resulting in infections in the fetus or newborns^[16–17].

Using neonatal infection as the dependent variable in this study, and the duration of PROM, length of the first stage, length of the second stage, nulliparity, placental inflammation, fetal tachycardia, prenatal fever, amniotic fluid contamination, and reproductive tract GBS colonization as independent variables, the analysis indicated that the duration of PROM,length of the first stage, length of the second stage, placental inflammation, fetal tachycardia, prenatal fever, amniotic fluid contamination, and GBS colonization were all independent risk factors for neonatal infection(p < 0.05).The OR values were 0.90, 1.18, 5.91, 20.11, 2.59, 7.03, 8.13, and 5.19, respectively.A possible explanation for this may be that pregnant women with a prolonged rupture of membranes experience a continuous flow of vaginal fluid, which increases the likelihood of pathogenic microorganisms entering the uterine cavity, thereby increasing the risk of neonatal infection ^[18].Additionally, the length of the first and second stages of labor also correlates with an increased risk of neonatal infections. As labor progresses, the risk of complications such as grade III amniotic fluid contamination and fetal distress increases, which can result in neonatal asphyxia. A weakened neonatal immune response further raises the risk of infection ^[19].GBS is a common opportunistic pathogen in clinical practice, and some pregnant women may have GBS colonization in the reproductive tract during late pregnancy^[20].When PROM occurs, the immune system is compromised, allowing GBS to invade the amniotic cavity through the ruptured membranes, leading to reproductive tract infections and complications such as chorioamnionitis, maternal sepsis, and neonatal pneumonia^[21–22].Pregnant women with reproductive tract infections may present with symptoms such as prenatal fever and fetal tachycardia, which are closely linked to subsequent neonatal infections ^[23].The presence of placental inflammation confirms an infection in the amniotic cavity and is also a risk factor for neonatal infection. This study collected prenatal WBC and CRP levels, finding that inflammatory markers were higher in the infected group compared to the uninfected group. This suggests that pregnant women in the infected group may have been at a higher risk of infection than those in the uninfected group.

This study further analyzed neonatal complications and found that, among the 500 pregnant women with premature rupture of membranes, 77 cases resulted in neonatal infections, yielding an infection rate of 15.4%. Of these 77 cases, 19 (24.6%) had pneumonia, 8 (10.4%) had respiratory distress syndrome, 10 (13.0%) had respiratory failure, 40 (52.0%) experienced early-onset neonatal infections, and 11 (14.3%) had severe infections among the 77 cases of neonatal infections.

In summary, there are multiple risk factors for neonatal infection in pregnant women with premature rupture of membranes, and the risk factors identified in this study warrant clinical attention.When PROM occurs in the present of one or more risk factors, it is important to aiminister antibiotics promptly to prevent infection, to terminate the pregnancy in a timely fashion, and to reduce risks of the newborns as soon as possible to prevent and decrease the occurrence of neonatal infections.The analysis of neonatal complications in this study offers valuable insights for clinical practice. However, this study has limitations, such as being a single-center study with a small sample size, which may introduce certain biases into the fingings. Future research should aim to expand the sample size and involve multiple-centers to improve the reliability of the results.

Ethics approval and consent to participate

Ethical approval and participation in this study were conducted in accordance with the ethical standards set forth in the Journal of the American Medical Association, as outlined in the 1964 Helsinki Declaration and its subsequent amendments or similar ethical standards. This study was approved by the Ethics Committee of Wenzhou People's Hospital in Zhejiang Province, China (Ethics Number: KY-2023-275, dated July 19, 2023).

Consent for publication

Not applicable

Availability of data and materials

The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.

Competitive interest

The author reports that there is no conflict of interest.

Funding

Medical and Health Technology Plan Project in Zhejiang Province (2024KY1627)

Wenzhou Basic Scientific Research Project(Y2023530)

Author's contributions

Xiaohong Yu: Project development, data collection, and manuscript writing.

Haiying Chen: Data collection.

Guoce Chen: Data collection and manuscript writing.

All authors have read and approved the final manuscript.

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No competing interests reported.

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Analysis of risk factors and complications of neonatal infection in 500 pregnant women with premature rupture of membranes

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Abstract

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Introduction

Methods

Result

2.1 Comparison of basic information between Two Groups

2.2 Univariate comparison of risk factors for neonatal infection between Two Groups

2.4 Analysis of neonatal complications

Discussion

Declarations

References

Additional Declarations

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