Anemia ; epidemiology ; China ; epidemiology ; Female ; Hemoglobins ; analysis ; Humans ; Pregnancy ; Pregnancy Complications, Hematologic ; epidemiology ; Pregnancy Trimesters

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

The prevalence of hypertensive disorders in China was much higher than that in the United States. Considering the large population with wide geographic area of China, we aimed to add more information regarding the risk factors for hypertensive disorders of pregnancy. A case-control study was performed on 373 hypertensive cases and 507 normotensive controls. Participants were recruited from 2008 to 2014 in Yichang Maternal and Child Health Care Center in Hubei province and Anyang Maternal and Child Health Care Hospital in Henan province, China. Socio-demographic factors, family- related factors, pregnancy-associated factors, factors related to daily life behaviors and psychosocial factors were investigated with respect to hypertensive disorders in pregnancy through well-designed questionnaire. Chi-square test, t-test, univariate logistic regression analysis, and multivariate logistic regression analysis were used to find the possible risk factors behind hypertensive disorders in pregnancy. The results showed that family history of cardiovascular diseases (OR=6.18, 95% CI, 2.37 to 16.14), history of pregnancy-induced hypertension (OR=16.64, 95% CI, 5.74 to 48.22), low maternal educational level (OR=2.81, 95% CI, 1.30 to 6.04), and poor relationship with their parents-in-law (OR=3.44, 95% CI, 1.55 to 7.59) had statistically significant associations with hypertensive disorders in pregnancy through multivariate logistic regression analysis. Increased maternal age, increased pre-pregnancy body mass index, living in rural area, low paternal education level, family history of hypertension, passive smoking one year before and/or in pregnancy, and poor sleeping quality were significantly associated with hypertensive disorders in pregnancy from univariate logistic regression analysis while the associations became uncertain when they were entered for multivariate logistic regression analysis. It was concluded that family history of cardiovascular diseases, history of pregnancy-induced hypertension, low maternal educational level, and poor relationship with their parents-in-law were independent risk factors for hypertensive disorders among Chinese pregnant women.
Adult ; China ; epidemiology ; Female ; Humans ; Hypertension ; epidemiology ; Pregnancy ; Pregnancy Complications, Cardiovascular ; epidemiology ; Risk Factors ; Young Adult

Adult ; China ; epidemiology ; Female ; Humans ; Pregnancy ; Pregnancy Complications ; epidemiology ; Sleep Wake Disorders ; epidemiology ; Surveys and Questionnaires

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 describe the trend of multiple pregnancies and to compare the results with single pregnancy in Beijing from 1996 to 2010. Prevalence rates of pregnancy complications were compared between multiple and single pregnancies.

METHODSIn 1996, 1997, 1998, 1999, 2000, 2005, 2010, live births in two hospitals in Beijing were included to describe the trend of multiple and single pregnancy. Case-retrospective analyses were used. Information was collected, including maternal age, fetus number, delivery mode, with/without pregnancy induced diseases as hypertension, diabetes or anemia, gender of the baby, birth-weight and gestation etc. Linear regression analyses were applied to assess the trend of birth-weight and the rates of prevalence.

RESULTS63 661 babies and 62 895 puerperal were involved in this study. From 1996 to 2010, prevalence of multiple pregnancies increased by 0.02%, prevalence of cesarean delivery among multiple pregnancy women increased by 2.25% and the proportion of women older than 30 years increased by 3.52% and 2.89% among multiple or single pregnancy women, annually. However, the birth-weight did not show obvious change in both multiple and single birth babies. No obvious change was observed in the prevalence of low birth weight. Prevalence rates of premature birth increased by 1.62% and 0.16% among multiple and single pregnancy women, annually. From 1996 to 2010, the mean values of birth-weight among single birth babies were larger than 3 250 grams and under 2 500 gram among multiple birth babies. Rates of prevalence on pregnancy induced hypertension and anemia were higher in multiple pregnancy women than in single pregnancy women. Differences of rates on prevalence rates of pregnancy diabetes between multiple and single pregnancy women were not statistically significant.

CONCLUSIONPrevalence of multiple pregnancies increased from 1995 to 2010 in Beijing. Mothers of multiples were more likely to get pregnancy complication than the single pregnancy women.

Adult ; China ; epidemiology ; Female ; Humans ; Infant, Newborn ; Pregnancy ; Pregnancy Complications ; epidemiology ; Pregnancy Outcome ; Pregnancy, Multiple ; Retrospective Studies

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

BACKGROUNDNo national research on maternal and fetal complications and outcomes has been carried out in the mainland of China in recent years. This study was to provide a scientific basis for better control of obstetrical and neonatal diseases and better allocation of medical resources by analyzing the epidemiological characteristics of obstetrical diseases in the mainland of China.

METHODSHospitalized obstetrical cases from 19 tertiary and 20 secondary hospitals in 14 provinces (nationally representative) during the period January 1, 2011 to December 31, 2011 were randomly selected. The general condition, pregnancy complications, and perinatal outcomes of the patients were studied.

RESULTSThe top five medical and surgical complications of pregnant women in the mainland of China were anemia (6.34%), uterine fibroids (2.69%), thyroid disease (1.11%), thrombocytopenia (0.59%), and heart disease (0.59%). The incidences of premature rupture of membranes (PROM), preterm birth, prolonged pregnancy, hypertensive disorders complicating pregnancy (HDCP), multiple pregnancy, intrahepatic cholestasis of pregnancy (ICP), placenta previa, placental abruption, postpartum hemorrhage, and amniotic fluid embolism were 15.27%, 7.04%, 6.71%, 5.35%, 1.57%, 1.22%, 1.14%, 0.54%, 3.26% and 0.06%, respectively. The incidences of anemia and prolonged pregnancy were significantly lower in tertiary than secondary hospitals (P < 0.001), whereas the incidence of uterine fibroids, thyroid diseases, thrombocytopenia, heart disease, PROM, preterm birth, HDCP, multiple pregnancy, ICP, placenta previa, and placental abruption were significantly higher in tertiary than secondary hospitals (P < 0.001). The cesarean section (CS) rate was 54.77%. The newborn sex ratio was 119:100, and 1.03% of the neonates were malformed. The percentages of low birth weight and fetal macrosomia in full-term babies were 2.10% and 7.09%, respectively.

CONCLUSIONSThe incidence of some obstetrical diseases is still high in the mainland of China. The CS rate is much higher than World Health Organization recommendations, in which CS delivery by maternal request (CDMR) accounted for a large proportion. The government should propose solutions to reduce CS rate, especially the rate of CDMR. Most obstetrical complications have higher incidence in tertiary hospitals compared with secondary hospitals. It is important to manage the health of pregnant women systematically, especially those with high-risk factors.

China ; epidemiology ; Female ; Genital Diseases, Female ; epidemiology ; Humans ; Infant, Newborn ; Infant, Newborn, Diseases ; epidemiology ; Pregnancy ; Pregnancy Complications ; epidemiology

Case-Control Studies ; Female ; HIV Infections ; epidemiology ; Humans ; Pregnancy ; Pregnancy Complications, Infectious ; epidemiology ; Risk Factors

Influenza is an acute respiratory infectious disease caused by influenza virus. Pregnancy is associated with physiologic and immunological changes that may increase the risk for influenza virus infection and influenza-related complications. Influenza vaccination is the most effective way to prevent influenza virus infection. WHO and many countries have classified pregnant women as a priority population for influenza vaccination, however, there are still many challenges for promoting influenza vaccination in pregnant women in China, influenza vaccination coverage in pregnant women remains low and some influenza vaccine package inserts list pregnancy as an absolute contraindication. In this paper, we summarize the research progress in the effects of influenza infection and influenza vaccination during pregnancy both at home and abroad, then discuss the strategies to promote influenza vaccination in pregnancy for the purpose of providing reference for the related research and policy development in China.
Pregnancy ; Female ; Humans ; Pregnant Women ; Influenza, Human/epidemiology* ; Pregnancy Complications, Infectious/epidemiology* ; Influenza Vaccines ; Vaccination ; Orthomyxoviridae