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Treatment of cervical intraepithelial neoplasia (CIN) is associated with an increased risk of preterm delivery (PTD) although the exact pathomechanism is not yet understood. Women with untreated CIN also seem to have an increased risk of PTD. It is unclear whether this is attributable to human papillomavirus (HPV) infection or other factors. We aimed to investigate whether HPV infection shortly before or during pregnancy, as well as previous treatment for CIN, is associated with an increased risk of PTD and other adverse obstetric and neonatal outcomes. This was a retrospective population-based register study of women with singleton deliveries registered in the Swedish Medical Birth Register 1999-2016 (n = 1,044,023). The study population had a mean age of 30.2 years (SD 5.2) and a mean body mass index of 25.4 kg/m2 (SD 3.0), and 44% of the women were nulliparous before delivery. Study groups were defined based on cervical HPV tests, cytology, and histology, as registered in the Swedish National Cervical Screening Registry. Women with a history of exclusively normal cytology (n = 338,109) were compared to women with positive HPV tests (n = 2,550) or abnormal cytology (n = 11,727) within 6 months prior to conception or during the pregnancy, women treated for CIN3 before delivery (n = 23,185), and women with CIN2+ diagnosed after delivery (n = 33,760). Study groups were compared concerning obstetric and neonatal outcomes by logistic regression, and comparisons were adjusted for socioeconomic and health-related confounders. HPV infection was associated with PTD (adjusted odds ratio [aOR] 1.19, 95% CI 1.01-1.42, p = 0.042), preterm prelabor rupture of membranes (pPROM) (aOR 1.52, 95% CI 1.18-1.96, p < 0.001), prelabor rupture of membranes (PROM) (aOR 1.24, 95% CI 1.08-1.42, p = 0.002), and neonatal mortality (aOR 2.69, 95% CI 1.25-5.78, p = 0.011). Treatment for CIN was associated with PTD (aOR 1.85, 95% CI 1.76-1.95, p < 0.001), spontaneous PTD (aOR 2.06, 95% CI 1.95-2.17, p < 0.001), pPROM (aOR 2.36, 95% CI 2.19-2.54, p < 0.001), PROM (aOR 1.11, 95% CI 1.05-1.17, p < 0.001), intrauterine fetal death (aOR 1.35, 95% CI 1.05-1.72, p = 0.019), chorioamnionitis (aOR 2.75, 95% CI 2.33-3.23, p < 0.001), intrapartum fever (aOR 1.24, 95% CI 1.07-1.44, p = 0.003), neonatal sepsis (aOR 1.55, 95% CI 1.37-1.75, p < 0.001), and neonatal mortality (aOR 1.79, 95% CI 1.30-2.45, p < 0.001). Women with CIN2+ diagnosed within 3 years after delivery had increased PTD risk (aOR 1.18, 95% CI 1.10-1.27, p < 0.001). Limitations of the study include the retrospective design and the fact that because HPV test results only became available in 2007, abnormal cytology was used as a proxy for HPV infection. In this study, we found that HPV infection shortly before or during pregnancy was associated with PTD, pPROM, PROM, and neonatal mortality. Previous treatment for CIN was associated with even greater risks for PTD and pPROM and was also associated with PROM, neonatal mortality, and maternal and neonatal infectious complications.

This multicenter study compared a prenatal assay of cell-free DNA with a standard method of screening for trisomies among women at average risk. The positive predictive values of cfDNA testing and standard screening for trisomy 21 were 80.9% and 3.4%, respectively. Screening for fetal aneuploidy with the use of cell-free DNA (cfDNA) obtained from maternal plasma was introduced in 2011. Such screening has been reported to have a detection rate for trisomy 21 (Down's syndrome) of more than 99%, with a false positive rate as low as 0.1%. 1 Thus, cfDNA testing appears to represent a substantial improvement over traditional multiple-marker screening. In practice, the use of this test could result in a significant reduction in diagnostic procedures. Although several large proof-of-principle studies have confirmed the high sensitivity and specificity of cfDNA testing for the detection of trisomy 21, most of these . . .

Background/Objectives To assess whether quality of maternal diet affects birth weight and the risk of small for gestational age (SGA) and/or large for gestational age (LGA) babies. Subjects/Methods This study is based on the Norwegian Mother and Child Cohort Study (MoBa) and includes 65,904 pregnant women who answered a validated food frequency questionnaire at mid-pregnancy. Three maternal dietary patterns were extracted based on characteristics of food items in each pattern. From these we created four non-overlapping groups: “high prudent,” “high Western,” “high traditional,” and “mixed”. We obtained information about birth weight from the Norwegian Medical Birth Registry and calculated birth weight z -scores, SGA, and LGA according to an ultrasound-based, population-based, and a customized growth standards. Associations were studied by linear and multiple logistic regression. Results Compared to the high Western group, the high prudent group was associated with lower birth weight ( β ultrasound z -scores −0.041 (95% confidence interval (CI): −0.068, −0.013)) and the high traditional group with higher birth weight ( β ultrasound 0.067 (95% CI: 0.040, 0.094)) for all three growth standards. The high prudent pattern was associated with increased SGA risk (SGA ultrasound odds ratio (OR) 1.25 (95% CI: 1.02, 1.54)) and decreased LGA risk (LGA population OR 0.84 (95% CI: 0.75, 0.94)), while the high traditional group on the contrary was associated with decreased SGA (SGA customized OR 0.92 (95% CI: 0.84, 0.99)) and increased LGA risk (LGA population OR 1.12 (95% CI: 1.02, 1.24)). Conclusions Food quality was associated with birth weight in this well-nourished Norwegian population. Food quality may affect a woman’s risk of giving birth to a SGA or LGA baby.

To characterize subgroups of preterm prelabor rupture of membranes (PPROM) and short-term neonatal outcomes based on the presence and absence of intraamniotic inflammation (IAI) and/or microbial invasion of the amniotic cavity (MIAC). One hundred and sixty-six Caucasian women with singleton pregnancies were included in this study. Amniotic fluid samples were obtained by transabdominal amniocentesis (n=166) and were assayed for interleukin-6 levels by a lateral flow immunoassay. The presence of Ureaplasma species, Mycoplasma hominis, Chlamydia trachomatis, and 16S rRNA was evaluated in the amniotic fluid. IAI was defined as amniotic fluid IL-6 values, measured by a point of care test, higher than 745 pg/mL. Microbial-associated IAI (IAI with MIAC) and sterile intraamniotic inflammation (IAI alone) were found in 21% and 4%, respectively, of women with PPROM. Women with microbial-associated IAI had higher microbial loads of Ureaplasma species in the amniotic fluid than women with MIAC alone. No differences in the short-term neonatal morbidity with respect to the presence of microbial-associated IAI, sterile IAI and MIAC alone were found after adjusting for the gestational age at delivery in women with PPROM. Microbial-associated but not sterile intraamniotic inflammation is common in Caucasian women with PPROM. The gestational age at delivery but not the presence of inflammation affects the short-term neonatal morbidity of newborns from PPROM pregnancies.

Preterm delivery risk is increased for women with a previous cesarean section, which are becoming more common worldwide. However, this risk is based on studies which have not fully accounted for selection bias, and the studied outcomes have been limited to the study of early deliveries. This study aimed to determine the impact of previous delivery modes on the incidence of deviant duration of subsequent pregnancies. This retrospective cohort study used clinical data registered in the Swedish Medical Birth Register. 612 935 women with their first two pregnancies and 157 581 women with their first three pregnancies were included. The outcome was the gestational duration of the last pregnancy of the series, depending on previous delivery modes. The associations were analysed with multivariable logistic regression (with the gestational duration categorised) and survival models including Cox regression analyses. When using standard logistic regression, previous cesarean section was associated with an increased risk of both spontaneous preterm birth (adjusted odds ratio [aOR] 1.67, 95% CI 1.57-1.77) and postterm birth (aOR 1.55, 95% CI 1.49-1.62). However, the more appropriate survival models only showed an association between cesarean section and longer gestational duration of the subsequent pregnancy (adjusted hazard ratio 0.72, 95% CI 0.71-0.73). The survival model handles bias related to management differences between the exposure and reference groups better than standard logistic regression, making it the statistical method of choice when conducting studies on this research topic. This study shows that the main association between cesarean section and the gestational duration of the subsequent pregnancy is the prolonging of it, which stands in contrast with previous research on the topic.

Many maternal traits are associated with a neonate's gestational duration, birth weight, and birth length. These birth outcomes are subsequently associated with late-onset health conditions. The causal mechanisms and the relative contributions of maternal and fetal genetic effects behind these observed associations are unresolved. Based on 10,734 mother-infant duos of European ancestry from the UK, Northern Europe, Australia, and North America, we constructed haplotype genetic scores using single-nucleotide polymorphisms (SNPs) known to be associated with adult height, body mass index (BMI), blood pressure (BP), fasting plasma glucose (FPG), and type 2 diabetes (T2D). Using these scores as genetic instruments, we estimated the maternal and fetal genetic effects underlying the observed associations between maternal phenotypes and pregnancy outcomes. We also used infant-specific birth weight genetic scores as instrument and examined the effects of fetal growth on pregnancy outcomes, maternal BP, and glucose levels during pregnancy. The maternal nontransmitted haplotype score for height was significantly associated with gestational duration (p = 2.2 × 10-4). Both maternal and paternal transmitted height haplotype scores were highly significantly associated with birth weight and length (p < 1 × 10-17). The maternal transmitted BMI scores were associated with birth weight with a significant maternal effect (p = 1.6 × 10-4). Both maternal and paternal transmitted BP scores were negatively associated with birth weight with a significant fetal effect (p = 9.4 × 10-3), whereas BP alleles were significantly associated with gestational duration and preterm birth through maternal effects (p = 3.3 × 10-2 and p = 4.5 × 10-3, respectively). The nontransmitted haplotype score for FPG was strongly associated with birth weight (p = 4.7 × 10-6); however, the glucose-increasing alleles in the fetus were associated with reduced birth weight through a fetal effect (p = 2.2 × 10-3). The haplotype scores for T2D were associated with birth weight in a similar way but with a weaker maternal effect (p = 6.4 × 10-3) and a stronger fetal effect (p = 1.3 × 10-5). The paternal transmitted birth weight score was significantly associated with reduced gestational duration (p = 1.8 × 10-4) and increased maternal systolic BP during pregnancy (p = 2.2 × 10-2). The major limitations of the study include missing and heterogenous phenotype data in some data sets and different instrumental strength of genetic scores for different phenotypic traits. We found that both maternal height and fetal growth are important factors in shaping the duration of gestation: genetically elevated maternal height is associated with longer gestational duration, whereas alleles that increase fetal growth are associated with shorter gestational duration. Fetal growth is influenced by both maternal and fetal effects and can reciprocally influence maternal phenotypes: taller maternal stature, higher maternal BMI, and higher maternal blood glucose are associated with larger birth size through maternal effects; in the fetus, the height- and metabolic-risk-increasing alleles are associated with increased and decreased birth size, respectively; alleles raising birth weight in the fetus are associated with shorter gestational duration and higher maternal BP. These maternal and fetal genetic effects may explain the observed associations between the studied maternal phenotypes and birth outcomes, as well as the life-course associations between these birth outcomes and adult phenotypes.

Preterm birth is the most common single cause of perinatal and infant mortality, affecting 15 million infants worldwide each year with global rates increasing. Understanding of risk factors remains poor, and preventive interventions have only limited benefit. Large differences exist in preterm birth rates across high income countries. We hypothesized that understanding the basis for these wide variations could lead to interventions that reduce preterm birth incidence in countries with high rates. We thus sought to assess the contributions of known risk factors for both spontaneous and provider-initiated preterm birth in selected high income countries, estimating also the potential impact of successful interventions due to advances in research, policy and public health, or clinical practice. We analyzed individual patient-level data on 4.1 million singleton pregnancies from four countries with very high human development index (Czech Republic, New Zealand, Slovenia, Sweden) and one comparator U.S. state (California) to determine the specific contribution (adjusting for confounding effects) of 21 factors. Both individual and population-attributable preterm birth risks were determined, as were contributors to cross-country differences. We also assessed the ability to predict preterm birth given various sets of known risk factors. Previous preterm birth and preeclampsia were the strongest individual risk factors of preterm birth in all datasets, with odds ratios of 4.6-6.0 and 2.8-5.7, respectively, for individual women having those characteristics. In contrast, on a population basis, nulliparity and male sex were the two risk factors with the highest impact on preterm birth rates, accounting for 25-50% and 11-16% of excess population attributable risk, respectively (p<0.001). The importance of nulliparity and male sex on population attributable risk was driven by high prevalence despite low odds ratios for individual women. More than 65% of the total aggregated risk of preterm birth within each country lacks a plausible biologic explanation, and 63% of difference between countries cannot be explained with known factors; thus, research is necessary to elucidate the underlying mechanisms of preterm birth and, hence, therapeutic intervention. Surprisingly, variation in prevalence of known risk factors accounted for less than 35% of the difference in preterm birth rates between countries. Known risk factors had an area under the curve of less than 0.7 in ROC analysis of preterm birth prediction within countries. These data suggest that other influences, as yet unidentified, are involved in preterm birth. Further research into biological mechanisms is warranted. We have quantified the causes of variation in preterm birth rates among countries with very high human development index. The paucity of explicit and currently identified factors amenable to intervention illustrates the limited impact of changes possible through current clinical practice and policy interventions. Our research highlights the urgent need for research into underlying biological causes of preterm birth, which alone are likely to lead to innovative and efficacious interventions.

Observational epidemiological studies indicate that maternal height is associated with gestational age at birth and fetal growth measures (i.e., shorter mothers deliver infants at earlier gestational ages with lower birth weight and birth length). Different mechanisms have been postulated to explain these associations. This study aimed to investigate the casual relationships behind the strong association of maternal height with fetal growth measures (i.e., birth length and birth weight) and gestational age by a Mendelian randomization approach. We conducted a Mendelian randomization analysis using phenotype and genome-wide single nucleotide polymorphism (SNP) data of 3,485 mother/infant pairs from birth cohorts collected from three Nordic countries (Finland, Denmark, and Norway). We constructed a genetic score based on 697 SNPs known to be associated with adult height to index maternal height. To avoid confounding due to genetic sharing between mother and infant, we inferred parental transmission of the height-associated SNPs and utilized the haplotype genetic score derived from nontransmitted alleles as a valid genetic instrument for maternal height. In observational analysis, maternal height was significantly associated with birth length (p = 6.31 × 10-9), birth weight (p = 2.19 × 10-15), and gestational age (p = 1.51 × 10-7). Our parental-specific haplotype score association analysis revealed that birth length and birth weight were significantly associated with the maternal transmitted haplotype score as well as the paternal transmitted haplotype score. Their association with the maternal nontransmitted haplotype score was far less significant, indicating a major fetal genetic influence on these fetal growth measures. In contrast, gestational age was significantly associated with the nontransmitted haplotype score (p = 0.0424) and demonstrated a significant (p = 0.0234) causal effect of every 1 cm increase in maternal height resulting in ~0.4 more gestational d. Limitations of this study include potential influences in causal inference by biological pleiotropy, assortative mating, and the nonrandom sampling of study subjects. Our results demonstrate that the observed association between maternal height and fetal growth measures (i.e., birth length and birth weight) is mainly defined by fetal genetics. In contrast, the association between maternal height and gestational age is more likely to be causal. In addition, our approach that utilizes the genetic score derived from the nontransmitted maternal haplotype as a genetic instrument is a novel extension to the Mendelian randomization methodology in casual inference between parental phenotype (or exposure) and outcomes in offspring.

Background Severe iodine deficiency impacts fertility and reproductive outcomes. The potential effects of mild-to-moderate iodine deficiency are not well known. The aim of this study was to examine whether iodine intake was associated with subfecundity (i.e. > 12 months trying to get pregnant), foetal growth, and adverse pregnancy outcomes in a mild-to-moderately iodine-deficient population. Methods We used the Norwegian Mother, Father and Child Cohort Study (MoBa) and included 78,318 pregnancies with data on iodine intake and pregnancy outcomes. Iodine intake was calculated using an extensive food frequency questionnaire in mid-pregnancy. In addition, urinary iodine concentration was available in a subsample of 2795 pregnancies. Associations were modelled continuously by multivariable regression controlling for a range of confounding factors. Results The median iodine intake from food was 121 μg/day and the median urinary iodine was 69 μg/L, confirming mild-to-moderate iodine deficiency. In non-users of iodine supplements ( n  = 49,187), low iodine intake (< 100–150 μg/day) was associated with increased risk of preeclampsia (aOR = 1.14 (95% CI 1.08, 1.22) at 75 vs. 100 μg/day, p overall < 0.001), preterm delivery before gestational week 37 (aOR = 1.10 (1.04, 1.16) at 75 vs. 100 μg/day, p overall = 0.003), and reduced foetal growth (− 0.08 SD (− 0.10, − 0.06) difference in birth weight z -score at 75 vs. 150 μg/day, p overall < 0.001), but not with early preterm delivery or intrauterine death. In planned pregnancies ( n  = 56,416), having an iodine intake lower than ~ 100 μg/day was associated with increased prevalence of subfecundity (aOR = 1.05 (1.01, 1.09) at 75 μg/day vs. 100 μg/day, p overall = 0.005). Long-term iodine supplement use (initiated before pregnancy) was associated with increased foetal growth (+ 0.05 SD (0.03, 0.07) on birth weight z -score, p  < 0.001) and reduced risk of preeclampsia (aOR 0.85 (0.74, 0.98), p  = 0.022), but not with the other adverse pregnancy outcomes. Urinary iodine concentration was not associated with any of the dichotomous outcomes, but positively associated with foetal growth ( n  = 2795, p overall = 0.017). Conclusions This study shows that a low iodine intake was associated with restricted foetal growth and a higher prevalence of preeclampsia in these mild-to-moderately iodine-deficient women. Results also indicated increased risk of subfecundity and preterm delivery. Initiating iodine supplement use in pregnancy may be too late.

Background Excisional treatment of cervical intraepithelial neoplasia (CIN) has been associated with increased risk of preterm delivery (PTD), although the underlying mechanism is as yet unclear. Studies on formalin-fixed excised tissue indicate that the risk increases with cone-length, but the magnitude of increase is uncertain, especially in case of minor excisions (≤10 mm), as well compared to women with untreated CIN during pregnancy. This study assesses the impact of cone-length at previous treatment for CIN as well as diagnosis of CIN during pregnancy on the risk of PTD. Methods A register-based cohort study in western Sweden linking cervical cytology, histology, and treatment data from the Swedish National Cervical Screening Registry to data on obstetric outcomes in singleton pregnancies 2008–2016 from the Swedish Medical Birth Registry. These groups were compared for PTD and other obstetric outcomes: (1) women with one excisional treatment ( n =3250, including a subgroup ( n =2408) with cone-length measured before fixation; (2) women with untreated CIN diagnosed during pregnancy ( n =1380); and (3) women with normal cytology ( n =42,398). Logistic regression analyses were adjusted for socioeconomic and health-related confounders. Results Treated women had increased risk of PTD (adjusted odds ratio (aOR) 1.60, 95% confidence interval (CI) 1.21–2.12), spontaneous PTD (aOR 1.95, 95% CI 1.40–2.72) and preterm prelabor rupture of membranes (pPROM) (aOR 2.74, 95% CI 1.66–4.51) compared to the CIN during pregnancy group. ORs were similar when compared to the normal cytology group. Risks of these outcomes increased with cone-length. Mean cone-length was 9.1 mm. Cone-length ≤10 mm was associated with increased risk of PTD (aOR 1.41, 95% CI 1.02–1.94), spontaneous PTD (aOR 1.73, 95% CI 1.18–2.54), and pPROM (aOR 2.44, 95% CI 1.40–4.28), compared to the CIN during pregnancy group. The PTD risk was similar for cone-lengths 3–10 mm, thereafter increasing by 15% with each additional millimeter. Conclusions This study suggests that all excisional treatment, including small cones, are associated with increased risk of PTD and pPROM. Risks increase further with cone-length. In women of reproductive age, clinicians should aim to remove all CIN but minimal healthy cervical tissue. Cone-length should be recorded at treatment, for future prenatal risk estimation.