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 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

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

OBJECTIVETo investigate the birth state of neonates and the disease spectrum of hospitalized neonates from a primary hospital, and compare with the national data of the same period.

METHODSA retrospective investigation was carried out in 1,434 neonates born or hospitalized in this hospital from January 2005 to December 2005.

RESULTSDuring the investigation period, there were 1,100 neonates born in the department of obstetrics. The incidence of premature birth was 2.3%. The caesarean birth accounted for 54.2%, significantly higher than the national average (49.2%, p<0.01). The neonatal mortality was 0.2%. The incidences of antepartum hemorrhage, threatened abortion, and pregnancy infection in preterm infant' s mothers were significantly higher than those in full-term infant' s mothers. A total of 344 neonates were admitted to the department of pediatrics during the investigation period. Preterm infants accounted for 38.0% which was higher than the national average (26.2%; p<0.01). Beside preterm infants, asphyxia, respiratory distress syndrome (RDS), sepsis and intracranial hemorrhage were shown to have a significantly higher proportion than the national averages. The mortality of hospitalized neonates was 0.9%.

CONCLUSIONSThe higher cesarean section rate should be controlled in our hospital. Prenatal health care and fetal monitoring should be strengthened to decrease the incidence of premature birth, RDS, sepsis and intracranial hemorrhage, thus reducing the mortality of neonates.

Adult ; Cesarean Section ; Female ; Hospitalization ; Humans ; Incidence ; Infant Mortality ; Infant, Newborn ; Infant, Premature, Diseases ; epidemiology ; Pregnancy ; Pregnancy Complications ; epidemiology ; Premature Birth ; epidemiology ; Retrospective Studies

OBJECTIVETo investigate the association between third trimester hemoglobin (Hb) concentrations and the risk of low birth weight and preterm delivery in a Chinese population.

METHODSSubjects were women who delivered in four cities/counties in Jiangsu and Zhejiang provinces, China, during the period of 1995 - 2000. Incidence of low birth weight and preterm delivery was calculated and compared among groups of women with different levels of Hb during the third trimester. Multiple logistic regression was used to address relationships between Hb levels and the risk of preterm delivery and low birth weight while controlling for potential confounding factors.

RESULTSThe overall prevalence of anemia during third trimester of pregnancy was 48.2% , mainly consisting of mild and moderate anemia. Mild and moderate anemia did not increase the risk of preterm delivery and low birth weight statistically. The lowest incidence of preterm delivery and low birth weight was found among pregnant women with Hb levels at 90-99 g/L. The risk for preterm delivery and low birth weight increased with either increasing or decreasing hemoglobin concentrations. However,there was no remarkable elevation of the risk when Hb was in the range of 70-119 g/L. Women with severe anemia (Hb< 70 g/L) had 80% higher risk (95% CI:1.0-3.3) of preterm delivery and a 4.0-fold higher risk (95 % CI :2. 1-7.5) of low birth weight compared with women with an Hb value of 90-99 g/L. In addition, women with a high Hb concentration (Hb> 130 g/L) had 20% higher risk (95 % CI: 1..0-1.4) of preterm delivery and 50 % higher risk (95 % CI: 1.2-1.9) of low birth weight.

CONCLUSIONA U-shape relationship was found between Hb concentration and the risk of preterm delivery and low birth weight. Severe anemia and high hemoglobin concentration were both associated with increased risk of preterm deliveries and low birth weight.

Adult ; Delivery, Obstetric ; Female ; Hemoglobins ; metabolism ; Humans ; Infant, Low Birth Weight ; Infant, Newborn ; Infant, Premature ; Pregnancy ; Pregnancy Trimester, Third ; Premature Birth ; blood ; epidemiology ; Risk Factors ; Young Adult

OBJECTIVETo understand the relationship between perinatal factors and congenital hypothyroidism (CH) and provide scientific evidence for the prevention of CH.

METHODSA case-control study was conducted among 125 neonates with CH (case group) and 375 neonates without CH (control group) in Fujian Neonatal Screening Center from January in 2012 to December in 2013. Univariate and multivariate logistic regression analysis were performed to identify the risk factors to CH during perinatal period.

RESULTSUnivariate logistic regression analysis indicated that compared with control group, gestational hypertension, gestational diabetes mellitus, gestational thyroid disease and older age of mother were the risk factors to CH, the difference was statistically significant (P < 0.05) and the risk of CH was higher in female babies, preterm babies, post-term babies low birth weight babies, macrosomia, twins, babies with birth defects and infection in cases group than those in control group, the difference was statistically significant (P < 0.05). Multivariate logistic analysis showed that older age of mother (OR = 2.518, 95% CI: 1.186-5.347), gestational diabetes mellitus (OR = 1.904, 95% CI: 1.190-3.045), gestational hypothyroidism or hyperthyroidism (OR = 12.883 and 30.797, 95% CI: 2.055-80.751 and 3.309-286.594), preterm birth (OR = 4.238, 95% CI: 1.269-14.155), and post-term birth (OR = 12.799, 95% CI: 1.257-130.327), low birth weight (OR = 3.505, 95% CI: 1.059-11.601), macrosomia (OR = 3.733, 95% CI: 1.415-9.851), twin or multiparous delivery (OR = 5.493, 95% CI: 1.701-17.735), birth defects (OR = 3.665, 95% CI: 1.604-8.371) and fetal distress (OR = 3.130, 95% CI: 1.317-7.440) were the high risk factors to CH (P < 0.05).

CONCLUSIONCH was correlated with mother's age, gestational diabetes, gestational thyroid disease as well as neonate's birth weight and gestational age, foetus number, fetal distress and other complicated birth defects at certain degree. More attention should be paid to perinatal care to reduce risk factors and the incidence of CH.

Birth Weight ; Case-Control Studies ; Congenital Hypothyroidism ; epidemiology ; Diabetes, Gestational ; epidemiology ; Female ; Gestational Age ; Humans ; Hypertension, Pregnancy-Induced ; epidemiology ; Incidence ; Infant, Newborn ; Infant, Premature ; Maternal Age ; Neonatal Screening ; Pregnancy ; Pregnancy Complications ; epidemiology ; Premature Birth ; Risk Factors ; Twins