No abstract available.
Epidemiology ; Premature Birth* ; Risk Factors

OBJECTIVE: To investigate the birth condition of preterm infants and the causes of preterm birth in Henan Province, China, and to provide a basis for the prevention and treatment of preterm birth. METHODS: An epidemiological investigation was conducted for live-birth preterm infants who were born in 53 hospitals in 17 cities of Henan Province from January 1, 2019 to December 31, 2019 to investigate the incidence rate of preterm birth, the distribution of gestational age and birth weight, the use of antenatal glucocorticoids, and the causes of preterm birth. RESULTS: The incidence rate of preterm birth was 5.84% (12 406/212 438) in the 53 hospitals. The proportions of preterm infants with gestational ages of < 28 weeks, 28 - < 32 weeks, 32 - < 34 weeks, and 34 - < 37 weeks were 1.58% (196/12 406), 11.46% (1 422/12 406), 15.18% (1 883/12 406), and 71.78% (8 905/12 406) respectively. The proportions of preterm infants with birth weights of < 1 000 g, 1 000- < 1 500 g, 1 500- < 2 500 g, 2 500- < 4 000 g, and ≥ 4 000 g were 1.95% (240/12 313), 8.54% (1 051/12 313), 49.53% (6 099/12 313), 39.59% (4 875/12 313), and 0.39% (48/12 313) respectively. The infants born by natural labor accounted for 28.76% (3 568/12 406), and those born by cesarean section accounted for 70.38% (8 731/12 406). The rate of use of antenatal glucocorticoids was 52.52% (6 293/11 983) for preterm infants and 68.69% (2 319/3 376) for the preterm infants with a gestational age of < 34 weeks. Iatrogenic preterm labor was the leading cause of preterm birth[40.06% (4 915/12 270)], followed by spontaneous preterm birth[30.16% (3 701/12 270)] and preterm birth due to premature rupture of membranes[29.78% (3 654/12 270)]. The top three causes of iatrogenic preterm birth were hypertensive disorders of pregnancy[47.12% (2 316/4 915)], fetal intrauterine distress[22.85% (1 123/4 915)], and placenta previa/placental abruption[18.07% (888/4 915)]. CONCLUSIONS There is a relatively low incidence rate of preterm birth in Henan Province, and late preterm infants account for a relatively high proportion. Iatrogenic preterm birth is the main cause of preterm birth in Henan Province, and hypertensive disorders of pregnancy and fetal intrauterine distress are the main causes of iatrogenic preterm birth.
Cesarean Section ; China/epidemiology* ; Female ; Humans ; Infant ; Infant, Newborn ; Infant, Premature ; Obstetric Labor, Premature ; Pregnancy ; Premature Birth/etiology*

OBJECTIVETo investigate the possible association between mother's periodontal status and preterm low birth weight (PLBW) in Beijing.

METHODSThe periodontal status of 83 women who bore a preterm low birth weight infant (PLBW group) and 44 women who bore a normal birth weight infant (NBW group) within two years in four hospitals in Beijing were evaluated. These women were all generally healthy. The clinical periodontal parameters including plaque index (PLI), probing depth (PD), attachment loss (AL) and bleeding index (BI) recorded.

RESULTSThe percentages of PD > or = 4 mm sites, AL > or = 2 mm sites and BOP(+) sites in two groups were 8.1% vs 6.9%, 12.8% vs 6.1% and 70.4% vs 66.9%, respectively, which showed significantly higher in PLBW group than in NBW group(P < 0.01, P < 0.001, P < 0.01).

CONCLUSIONSThere was possible association between mother's periodontal status and preterm low birth weight in the investigated area. Poor periodontal status may be one of the risk factors of PLBW.

China ; epidemiology ; Female ; Humans ; Infant, Low Birth Weight ; Mothers ; Periodontal Diseases ; epidemiology ; Premature Birth ; etiology ; Risk Factors

OBJECTIVETo describe the secular trends and epidemiological characteristics of preterm birth among singletons in 10 counties (cities) of China during 1993-2005.

METHODSWe analyzed data on 542 923 women (gestational age > or =28 weeks) collected through Perinatal Healthcare Surveillance System established by the Institute of Reproductive and Child Health, Peking University. Chi-square tests were employed to test the differences in prevalence of preterm birth among different groups.

RESULTS25 784 preterm births were identified, including 1530 stillbirths. Preterm birth rate was 4.75% (95% CI:4.69-4.81) for all births and 4.49% (95% CI:4.44-4.55) for live births. Preterm birth rate declined steadily from 1993 to 2005 and had no significant seasonal variation. Preterm birth rate from the urban areas of the Southern part of the country,was higher than that in the rural areas which was also higher than that seen in the rural areas from the northern part of the country. Relations between women's age at delivery and preterm birth appeared to be U-shaped. Increased preterm birth rates were also observed in women with lower education level,more parities,and previous history of preterm birth or abortion.

CONCLUSIONPreterm birth rate decreased steadily from 1993-2005 in 10 counties (cities) but varied by areas of the country.

Adult ; Birth Rate ; trends ; China ; epidemiology ; Female ; Humans ; Pregnancy ; Premature Birth ; epidemiology ; Prevalence ; Rural Population ; Urban Population ; Young Adult

China ; epidemiology ; Disease Outbreaks ; Female ; Humans ; Pregnancy ; Premature Birth ; epidemiology ; Risk Factors

BACKGROUND: Extreme temperature events, including extreme cold, are becoming more frequent worldwide, which might be harmful to pregnant women and cause adverse birth outcomes. We aimed to investigate the association between exposure to low ambient temperature in pregnant women and adverse birth outcomes, such as preterm birth, low birth weight, and stillbirth, and to summarize the evidence herein. METHODS: Relevant studies were searched in PubMed, Cochrane, and Embase electronic databases until November 2021. Studies involving low ambient temperature, preterm birth, birth weight, and stillbirth were included. The guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analyses were followed to conduct this study risk of bias and methods for data synthesis. RESULTS: A total of 34 studies were included. First, pregnant women exposed to low ambient temperature had an increased risk of preterm birth (risk ratio [RR] 1.08; 95% confidence interval [CI] 1.04-1.13). Subgroup analyses revealed that exposure during late pregnancy was more likely to induce preterm birth. In addition, only pregnant women exposed to <1st percentile of the mean temperature suffered increased risk of preterm birth. Moreover, pregnant women living in medium or hot areas were more prone to have preterm births than those in cold areas when exposed to low ambient temperatures. Asians and Blacks were more susceptible to low ambient temperatures than Caucasians. Second, pregnant women exposed to low ambient temperature had an increased risk of low birth weight (RR 1.07; 95% CI 1.03-1.12). Third, pregnant women had an increased risk of stillbirth while exposed to low ambient temperature during the entire pregnancy (RR 4.63; 95% CI 3.99-5.38). CONCLUSIONS: Exposure to low ambient temperature during pregnancy increases the risk of adverse birth outcomes. Pregnant women should avoid exposure to extremely low ambient temperature (<1st percentile of the mean temperature), especially in their late pregnancy. This study could provide clues for preventing adverse outcomes from meteorological factors. REGISTRATION No. CRD42021259776 at PROSPERO ( https://www.crd.york.ac.uk/PROSPERO/ ).
Pregnancy ; Infant, Newborn ; Female ; Humans ; Pregnancy Outcome ; Premature Birth/epidemiology* ; Stillbirth/epidemiology* ; Temperature ; Pregnancy Complications

OBJECTIVETo measure the incidence rates of preterm delivery in HIV-infected pregnant women and to explore related potential risk factors.

METHODSData from 'Information System of Prevention of Mother-to-child Transmission of HIV Management in China, 2013' was used in the study. Information regarding demographic characteristics, pregnancy, HIV relevant situations and pregnancy outcomes related to these HIV-infected pregnant women, were extracted and analyzed. Incidence of preterm delivery was calculated with related potential risk factors explored.

RESULTS3 913 HIV-infected pregnant women were involved in this study, including 336 of them having undergone preterm deliveries (8.6%). Results from univariate and multivariate analyses showed that preterm delivery was associated with factors as: maternal age, ethnicity, education, being migrant, pregnancy hypertension, multiple pregnancy and times of antenatal care visits (P < 0.05) of the pregnant women. Compared with those who contracted the HIV infection through drug injection, the ones who were infected through other routes suffered fewer preterm deliveries (adjusted OR = 0.562, 95% CI: 0.360-0.879). Pregnant women who received antiretroviral therapy either between 14 to 27 gestational weeks or during the period of less than 14, were more likely to experience preterm delivery, comparison to those who did not receive the therapy during pregnancy. The adjusted ORs were 1.712 (95% CI: 1.196-2.451) and 1.862 (95% CI: 1.261-2.749), respectively.

CONCLUSIONPreterm delivery was a common adverse outcome during pregnancy among HIV-infected women in China. Other than traditionally known risk factors, routes of transmission and the use of antiretroviral therapy might also be associated with the increased risks for preterm delivery.

China ; epidemiology ; Female ; HIV Infections ; epidemiology ; Humans ; Incidence ; Infant, Newborn ; Pregnancy ; Pregnancy Complications, Infectious ; epidemiology ; Premature Birth ; epidemiology ; Risk Factors

OBJECTIVETo understand the distribution of birth weight among premature infants and the associated social factors.

METHODSThe study population consisted of 97 537 women who delivered singleton live birth of 20 to 41 gestational weeks in 4 counties/cities, Jiangsu and Zhejiang provinces, China from 1995 to 2000. Chi-square test was employed to test the difference of proportions between respective groups. One- way ANOVA was used to test the differences regarding the mean of gestational weeks at the first prenatal visit and the mean of prenatal visits between the two groups. Multivariate logistic regression was conducted to examine the factors associated with premature birth.

RESULTSWomen aged 35 years had higher (8.8%) premature incidence than those aged less than 24 years (5.6%), 25 - 29 years (4.6%), or 30 - 34 years (4.5%, P < 0.001). Women with height less than 149 cm had higher (6.8%) premature incidence than those with height taller than 150 cm (5.0%). Women whose BMI were at least 28 and 24 - 28 had higher (5.5%, 5.5%) premature incidences than those whose BMI were 18.5 - 24.0 (5.0%), < 18.5 (4.6%, P < 0.001). The incidence of premature birth was 6.0% among women without previous pregnancy, higher than that among those women with 4 times of pregnancies (5.7%), 2 times of pregnancies (4.3%), and 3 times of pregnancies (4.0%). Parous women with at least two deliveries had higher (9.3%) premature incidence than the primiparous women (5.2%) and whose women with only one delivery (4.5%, P < 0.001). Women who received early prenatal care had lower 4.7% premature incidence than those who did not receive the service (6.1%). The mean times of prenatal visits among women with premature births was 8.53, less than that of those with full term delivery (10.97). Women with less than four times of prenatal visit had higher (18.9%) premature incidence than those with at least five prenatal visits (4.9%). Multivariate logistic regression showed that premature delivery risk was associated with age, height, BMI, gravidity, parity, early prenatal care, the mean of gestational weeks at first prenatal visit and the mean number of prenatal visits etc.

CONCLUSIONPremature delivery risk was associated with factors as age, height, BMI, gravidity, parity, early prenatal care, the mean of gestational weeks at first prenatal visit, the mean number of prenatal visits etc.

Adult ; Birth Weight ; China ; epidemiology ; Female ; Humans ; Incidence ; Infant, Low Birth Weight ; Infant, Newborn ; Infant, Premature ; Infant, Premature, Diseases ; epidemiology ; Pregnancy ; Risk Factors ; Socioeconomic Factors

OBJECTIVE: To describe the thyroid function abnormality of first-trimester twin pregnant women according to different references, and to explore its association with preterm delivery. METHODS: Participants, first-trimester twin pregnant women, were recruited at Peking University Third Hospital from March 2017 to February 2020. The thyroid hormone reference for ordinary adults identified on the assay kits by Siemens incorporation, thyroid hormone reference specifically for singleton pregnancy established previously, and thyroid hormone reference specifically for twin pregnancy established previously were used in the description of hypothyroidism and hyperthyroidism for first-trimester twin pregnant women. Thyroid autoantibody reference identified on the assay kits by Siemens incorporation was used in the description of positive thyroid autoantibody. Multivariable log-binomial regression was conducted to examine the association between thyroid function and preterm delivery, in which normal pregnant women according to the three references and normal pregnant women according to twin pregnancy reference accompanied with negative thyroid autoantibody were taken as control respectively. RESULTS: A total of 570 twin pregnant women were finally included. Rates of hypothyroidism according to the three references were 1.2%, 1.6% and 3.5%, respectively. Rates of hyperthyroidism according to the three references were 32.6%, 18.1% and 1.1%, respectively. After adjustment for potential confounding factors, risk of preterm delivery significantly increased in pregnant women with hyperthyroidism according to the twin specific pregnancy reference [adjusted relative risk (ARR)=1.41, 95%CI: 1.14-1.75], while no significant increase was found in those with normal thyroid function according to the twin specific pregnancy reference but hyperthyroidism according to the singleton specific pregnancy reference (ARR=1.00, 95%CI: 0.81-1.25) and in those with hyperthyroidism purely according to the ordinary adult reference (ARR=1.06, 95%CI: 0.85-1.32), compared with those normal according to all the references. Risks of preterm delivery almost significantly or significantly increased in pregnant women with hypothyroidism according to the ordinary adult or singleton specific pregnancy reference (ARR=1.40, 95%CI: 0.88-2.22) and those with hypothyroidism according to the twin specific pregnancy reference (ARR=1.53, 95%CI: 1.03-2.28). Overall analysis of thyroid function according to the twin specific pregnancy reference and thyroid autoantibody showed that risks of preterm delivery almost significantly or significantly increased in pregnant women with simple hypothyroidism (ARR=1.46, 95%CI: 0.93-2.27), simple positive thyroid autoantibody (ARR=1.32, 95%CI: 1.15-1.52), and hypothyroidism accompanied with positive thyroid autoantibody (ARR=1.78, 95%CI: 1.30-2.44), compared with those normal according to the twin specific pregnancy reference with negative thyroid autoantibody. CONCLUSION The ordinary adult reference and that of singleton pregnancy may lead to under-diagnosis of hypothyroidism and over-diagnosis of hyperthyroidism in first-trimester twin pregnant women. Compared with pregnant women with normal thyroid function, those missed in the diagnosis of hypothyroidism were at a higher risk of preterm delivery, while those over-diagnosed as hyperthyroidism had a similar risk of preterm delivery, indicating a need to develop and generalize twin-pregnancy-specific reference on common indicators of thyroid function. Moreover, the thyroid autoantibody should be taken into consideration in the prenatal diagnosis and treatment to twin pregnant women with hypothyroidism.
Adult ; Female ; Humans ; Hypothyroidism/epidemiology* ; Infant, Newborn ; Pregnancy ; Pregnancy Complications/epidemiology* ; Pregnancy Trimester, First ; Pregnant Women ; Premature Birth/epidemiology*

OBJECTIVETo determine the association between pregnancy-induced hypertension(PIH) and risk of preterm delivery (PD) and low birth weight (LBW).

METHODSA prospective cohort was established based on 131 867 women who delivered a singleton baby in seven cities or counties in Zhejiang province, China, during the period of 1995 - 2000. The exposure group included 14 278 women who were diagnosed as PIH, and the non-exposure group included 117 589 women. The exposure group was divided into mild, moderate, and severe subgroups based on the severity of PIH, and further divided into early, medium and late onset subgroups based on the time of onset of PIH (occurred in second trimester, third trimester, or during delivery). The primary outcome measures were the incidence of PD and LBW. Multiple logistic regression was used to estimate relative risk and 95% confidence intervals after adjustment by maternal age, occupation, education, parity, number of prenatal visits, gestational disease, caesarean delivery, pregnant body mass index, fetal sex, and gestational age (only for LBW).

RESULTSThe incidence rates of PD and LBW in exposure group were 4.9% (701/14 278) and 3.6% (507/14 278), and both rates were higher than those of the non-exposure group (3.4% (4031/117 589), 1.8% (2110/117 589)) (chi(2) values were 80.8 and 202.0, P < 0.001). The incidence rates of PD in mild, moderate, and severe subgroups were 3.9% (404/10 358), 5.8% (181/3099), and 14.1% (116/821), and corresponding incidence rates of LBW were 2.5% (258/10 358), 4.9% (151/3099), and 11.9% (98/821). Both rates were increased with the severity of PIH (chi(2) values were 196.4 and 426.1, P-value for trend < 0.001). The incidence rates of PD in early, medium, and late onset subgroup were 8.4% (50/598), 5.7% (278/4867), and 4.2% (373/8813), and corresponding incidence rates of LBW were 5.7% (34/598), 4.2% (206/4867), and 3.0% (267/8813). Both rates were decreased by the time of PIH onset (chi(2) values were 115.4 and 239.8, P-value for trend < 0.001).

CONCLUSIONPIH could increase the incidence of PD and LBW.

Adult ; Female ; Humans ; Hypertension, Pregnancy-Induced ; epidemiology ; Infant, Low Birth Weight ; Infant, Newborn ; Pregnancy ; Premature Birth ; Prospective Studies ; Young Adult