Epidemiology and causes of preterm birth Goldenberg, Robert L, Prof; Culhane, Jennifer F, PhD; Iams, Jay D, Prof ...
The Lancet (British edition),
01/2008, Volume:
371, Issue:
9606
Journal Article
Peer reviewed
Open access
Summary This paper is the first in a three-part series on preterm birth, which is the leading cause of perinatal morbidity and mortality in developed countries. Infants are born preterm at less than ...37 weeks' gestational age after: (1) spontaneous labour with intact membranes, (2) preterm premature rupture of the membranes (PPROM), and (3) labour induction or caesarean delivery for maternal or fetal indications. The frequency of preterm births is about 12–13% in the USA and 5–9% in many other developed countries; however, the rate of preterm birth has increased in many locations, predominantly because of increasing indicated preterm births and preterm delivery of artificially conceived multiple pregnancies. Common reasons for indicated preterm births include pre-eclampsia or eclampsia, and intrauterine growth restriction. Births that follow spontaneous preterm labour and PPROM—together called spontaneous preterm births—are regarded as a syndrome resulting from multiple causes, including infection or inflammation, vascular disease, and uterine overdistension. Risk factors for spontaneous preterm births include a previous preterm birth, black race, periodontal disease, and low maternal body-mass index. A short cervical length and a raised cervical-vaginal fetal fibronectin concentration are the strongest predictors of spontaneous preterm birth.
Summary Interventions to reduce the morbidity and mortality of preterm birth can be primary (directed to all women), secondary (aimed at eliminating or reducing existing risk), or tertiary (intended ...to improve outcomes for preterm infants). Most efforts so far have been tertiary interventions, such as regionalised care, and treatment with antenatal corticosteroids, tocolytic agents, and antibiotics. These measures have reduced perinatal morbidity and mortality, but the incidence of preterm birth is increasing. Advances in primary and secondary care, following strategies used for other complex health problems, such as cervical cancer, will be needed to prevent prematurity-related illness in infants and children.
This paper is the first in a three-part series on preterm birth, which is the leading cause of perinatal morbidity and mortality in developed countries. Infants are born preterm at less than 37 ...weeks' gestational age after: (1) spontaneous labour with intact membranes, (2) preterm premature rupture of the membranes (PPROM), and (3) labour induction or caesarean delivery for maternal or fetal indications. The frequency of preterm births is about 12-13% in the USA and 5-9% in many other developed countries; however, the rate of preterm birth has increased in many locations, predominantly because of increasing indicated preterm births and preterm delivery of artificially conceived multiple pregnancies. Common reasons for indicated preterm births include pre-eclampsia or eclampsia, and intrauterine growth restriction. Births that follow spontaneous preterm labour and PPROM-together called spontaneous preterm births-are regarded as a syndrome resulting from multiple causes, including infection or inflammation, vascular disease, and uterine overdistension. Risk factors for spontaneous preterm births include a previous preterm birth, black race, periodontal disease, and low maternal body-mass index. A short cervical length and a raised cervical-vaginal fetal fibronectin concentration are the strongest predictors of spontaneous preterm birth. PUBLICATION ABSTRACT
Care for women with prior preterm birth Iams, Jay D., MD; Berghella, Vincenzo, MD
American journal of obstetrics and gynecology,
08/2010, Volume:
203, Issue:
2
Journal Article
Peer reviewed
Open access
Women who have delivered an infant between 16 and 36 weeks' gestation have an increased risk of preterm birth in subsequent pregnancies. The risk increases with more than 1 preterm birth and is ...inversely proportional to the gestational age of the previous preterm birth. African American women have rates of recurrent preterm birth that are nearly twice that of women of other backgrounds. An approximate risk of recurrent preterm birth can be estimated by a comprehensive reproductive history, with emphasis on maternal race, the number and gestational age of prior births, and the sequence of events preceding the index preterm birth. Interventions including smoking cessation, eradication of asymptomatic bacteriuria, progestational agents, and cervical cerclage can reduce the risk of recurrent preterm birth when employed appropriately.
The preterm birth rate in the United States declined to 11.4% in 2013, the lowest level since 1997. Although the United States has one of the highest preterm birth rates in the developed world, we ...are improving this outcome and therefore improving the lives of thousands of infants. Demographic changes that may be responsible include a reduced teenage birth rate and fewer higher-order multiple births. Additionally, a public policy shift to prevent nonmedically indicated births at <39 weeks’ gestation and smoking bans in several states have been associated with the reduced rate of preterm births. Last, interventions such as 17 hydroxyprogesterone caproate, vaginal progesterone, and the use of cerclage in selected populations probably are contributing to the reduction in preterm deliveries. However, a large portion of these births could still be prevented with greater access and implementation of our current interventions, the reduction of modifiable risk factors for preterm birth, and expanded reporting of outcomes and risk factors to facilitate research for both prevention and treatment.
Subclinical thyroid disease during pregnancy may be associated with adverse outcomes, including a lower-than-normal IQ in offspring. It is unknown whether levothyroxine treatment of women who are ...identified as having subclinical hypothyroidism or hypothyroxinemia during pregnancy improves cognitive function in their children.
We screened women with a singleton pregnancy before 20 weeks of gestation for subclinical hypothyroidism, defined as a thyrotropin level of 4.00 mU or more per liter and a normal free thyroxine (T
) level (0.86 to 1.90 ng per deciliter 11 to 24 pmol per liter), and for hypothyroxinemia, defined as a normal thyrotropin level (0.08 to 3.99 mU per liter) and a low free T
level (<0.86 ng per deciliter). In separate trials for the two conditions, women were randomly assigned to receive levothyroxine or placebo. Thyroid function was assessed monthly, and the levothyroxine dose was adjusted to attain a normal thyrotropin or free T
level (depending on the trial), with sham adjustments for placebo. Children underwent annual developmental and behavioral testing for 5 years. The primary outcome was the IQ score at 5 years of age (or at 3 years of age if the 5-year examination was missing) or death at an age of less than 3 years.
A total of 677 women with subclinical hypothyroidism underwent randomization at a mean of 16.7 weeks of gestation, and 526 with hypothyroxinemia at a mean of 17.8 weeks of gestation. In the subclinical hypothyroidism trial, the median IQ score of the children was 97 (95% confidence interval CI, 94 to 99) in the levothyroxine group and 94 (95% CI, 92 to 96) in the placebo group (P=0.71). In the hypothyroxinemia trial, the median IQ score was 94 (95% CI, 91 to 95) in the levothyroxine group and 91 (95% CI, 89 to 93) in the placebo group (P=0.30). In each trial, IQ scores were missing for 4% of the children. There were no significant between-group differences in either trial in any other neurocognitive or pregnancy outcomes or in the incidence of adverse events, which was low in both groups.
Treatment for subclinical hypothyroidism or hypothyroxinemia beginning between 8 and 20 weeks of gestation did not result in significantly better cognitive outcomes in children through 5 years of age than no treatment for those conditions. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Institute of Neurological Disorders and Stroke; ClinicalTrials.gov number, NCT00388297 .).
Objective The objective of the study was to assess cerclage to prevent recurrent preterm birth in women with short cervix. Study Design Women with prior spontaneous preterm birth less than 34 weeks ...were screened for short cervix and randomly assigned to cerclage if cervical length was less than 25 mm. Results Of 1014 women screened, 302 were randomized; 42% of women not assigned and 32% of those assigned to cerclage delivered less than 35 weeks ( P = .09). In planned analyses, birth less than 24 weeks ( P = .03) and perinatal mortality ( P = .046) were less frequent in the cerclage group. There was a significant interaction between cervical length and cerclage. Birth less than 35 weeks ( P = .006) was reduced in the less than 15 mm stratum with a null effect in the 15-24 mm stratum. Conclusion In women with a prior spontaneous preterm birth less than 34 weeks and cervical length less than 25 mm, cerclage reduced previable birth and perinatal mortality but did not prevent birth less than 35 weeks, unless cervical length was less than 15 mm.
Objective The primary aim of the “Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be” is to determine maternal characteristics, which include genetic, physiologic response to pregnancy, ...and environmental factors that predict adverse pregnancy outcomes. Study Design Nulliparous women in the first trimester of pregnancy were recruited into an observational cohort study. Participants were seen at 3 study visits during pregnancy and again at delivery. We collected data from in-clinic interviews, take-home surveys, clinical measurements, ultrasound studies, and chart abstractions. Maternal biospecimens (serum, plasma, urine, cervicovaginal fluid) at antepartum study visits and delivery specimens (placenta, umbilical cord, cord blood) were collected, processed, and stored. The primary outcome of the study was defined as pregnancy ending at <37+0 weeks’ gestation. Key study hypotheses involve adverse pregnancy outcomes of spontaneous preterm birth, preeclampsia, and fetal growth restriction. Results We recruited 10,037 women to the study. Basic characteristics of the cohort at screening are reported. Conclusion The “Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be” cohort study methods and procedures can help investigators when they plan future projects.
Abstract Background The significance of periconceptional nutrition for optimizing offspring and maternal health and reducing social inequalities warrants greater understanding of diet quality among ...US women. Objective Our objective was to evaluate racial or ethnic and education inequalities in periconceptional diet quality and sources of energy and micronutrients. Design Cross-sectional analysis of data from the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be cohort. Participants and setting Nulliparous women (N=7,511) were enrolled across eight US medical centers from 2010 to 2013. Main outcome measures A semiquantitative food frequency questionnaire assessing usual dietary intake during the 3 months around conception was self-administered during the first trimester. Diet quality, measured using the Healthy Eating Index-2010 (HEI-2010), and sources of energy and micronutrients were the outcomes. Statistical analyses Differences in diet quality were tested across maternal racial or ethnic and education groups using F tests associated with analysis of variance and χ2 tests. Results HEI-2010 score increased with higher education, but the increase among non-Hispanic black women was smaller than among non-Hispanic whites and Hispanics (interaction P value <0.0001). For all groups, average scores for HEI-2010 components were below recommendations. Top sources of energy were sugar-sweetened beverages, pasta dishes, and grain desserts, but sources varied by race or ethnicity and education. Approximately 34% of energy consumed was from empty calories (the sum of energy from added sugars, solid fats, and alcohol beyond moderate levels). The primary sources of iron, folate, and vitamin C were juices and enriched breads. Conclusions Diet quality is suboptimal around conception, particularly among women who are non-Hispanic black, Hispanic, or who had less than a college degree. Diet quality could be improved by substituting intakes of refined grains and foods empty in calories with vegetables, peas and beans (legumes), seafood, and whole grains.
Background Preterm delivery remains the leading cause of perinatal mortality. Risk factors and biomarkers have traditionally failed to identify the majority of preterm deliveries. Objective To ...develop and validate a mass spectrometry–based serum test to predict spontaneous preterm delivery in asymptomatic pregnant women. Study Design A total of 5501 pregnant women were enrolled between 170/7 and 286/7 weeks gestational age in the prospective Proteomic Assessment of Preterm Risk study at 11 sites in the United States between 2011 and 2013. Maternal blood was collected at enrollment and outcomes collected following delivery. Maternal serum was processed by a proteomic workflow, and proteins were quantified by multiple reaction monitoring mass spectrometry. The discovery and verification process identified 2 serum proteins, insulin-like growth factor–binding protein 4 (IBP4) and sex hormone–binding globulin (SHBG), as predictors of spontaneous preterm delivery. We evaluated a predictor using the log ratio of the measures of IBP4 and SHBG (IBP4/SHBG) in a clinical validation study to classify spontaneous preterm delivery cases (<370/7 weeks gestational age) in a nested case-control cohort different from subjects used in discovery and verification. Strict blinding and independent statistical analyses were employed. Results The predictor had an area under the receiver operating characteristic curve value of 0.75 and sensitivity and specificity of 0.75 and 0.74, respectively. The IBP4/SHBG predictor at this sensitivity and specificity had an odds ratio of 5.04 for spontaneous preterm delivery. Accuracy of the IBP4/SHBG predictor increased using earlier case-vs-control gestational age cutoffs (eg, <350/7 vs ≥350/7 weeks gestational age). Importantly, higher-risk subjects defined by the IBP4/SHBG predictor score generally gave birth earlier than lower-risk subjects. Conclusion A serum-based molecular predictor identifies asymptomatic pregnant women at risk of spontaneous preterm delivery, which may provide utility in identifying women at risk at an early stage of pregnancy to allow for clinical intervention. This early detection would guide enhanced levels of care and accelerate development of clinical strategies to prevent preterm delivery.
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