Fetal size in a rural melanesian population with minimal risk factors for growth restriction: an observational ultrasound study from Papua New Guinea

Mycoplasma genitalium in pregnancy, including specific co-infections, is associated with lower birthweight: A prospective cohort study

BACKGROUND

Mycoplasma genitalium infection in pregnancy is increasingly reported at similar frequencies to other sexually transmitted infections (STIs). Knowledge on its contribution to adverse pregnancy outcomes is very limited, especially relative to other STIs or bacterial vaginosis (BV). Whether M. genitalium influences birthweight remains unanswered.

METHODS

Associations between birthweight and M. genitalium and other STIs (Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis) and BV in pregnancy were examined in 416 maternal-newborn pairs from a prospective cohort study in Papua New Guinea.

FINDINGS

Compared to uninfected women, M. genitalium (-166.9 g, 95% confidence interval [CI]: -324.2 to -9.7 g, p = 0.038) and N. gonorrhoeae (-274.7 g, 95% CI: -561.9 to 12.5 g, p = 0.061) infections were associated with lower birthweight in an adjusted analysis. The association for C. trachomatis was less clear, and T. vaginalis and BV were not associated with lower birthweight. STI prevalence was high for M. genitalium (13.9%), N. gonorrhoeae (5.0%), and C. trachomatis (20.0%); co-infections were frequent. Larger effect sizes on birthweight occurred with co-infections of M. genitalium, N. gonorrhoeae, and/or C. trachomatis.

CONCLUSION

M. genitalium is a potential contributor to lower birthweight, and co-infections appear to have a greater negative impact on birthweight. Trials examining the impact of early diagnosis and treatment of M. genitalium and other STIs in pregnancy and preconception are urgently needed.

FUNDING

Funding was received from philanthropic grants, the National Health and Medical Research Council, and the Burnet Institute. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Effects of Plasmodium falciparum infection on umbilical artery resistance and intrafetal blood flow distribution: a Doppler ultrasound study from Papua New Guinea

Background

Doppler velocimetry studies of umbilical artery (UA) and middle cerebral artery (MCA) flow help to determine the presence and severity of fetal growth restriction. Increased UA resistance and reduced MCA pulsatility may indicate increased placental resistance and intrafetal blood flow redistribution. Malaria causes low birth weight and fetal growth restriction, but few studies have assessed its effects on uteroplacental and fetoplacental blood flow.

Methods

Colour-pulsed Doppler ultrasound was used to assess UA and MCA flow in 396 Papua New Guinean singleton fetuses. Abnormal flow was defined as an UA resistance index above the 90th centile, and/or a MCA pulsatility index and cerebroplacental ratio (ratio of MCA and UA pulsatility index) below the 10th centile of population-specific models fitted to the data. Associations between malaria (peripheral infection prior to and at ultrasound examination, and any gestational infection, i.e., ‘exposure’) and abnormal flow, and between abnormal flow and birth outcomes, were estimated.

Results

Of 78 malaria infection episodes detected before or at the ultrasound visit, 62 (79.5%) were Plasmodium falciparum (34 sub-microscopic infections), and 16 were Plasmodium vivax. Plasmodium falciparum infection before or at Doppler measurement was associated with increased UA resistance (adjusted odds ratio (aOR) 2.3 95% CI 1.0–5.2, P = 0.047). When assessed by ‘exposure’, P. falciparum infection was significantly associated with increased UA resistance (all infections: 2.4, 1.1–4.9, P = 0.024; sub-microscopic infections 2.6, 1.0–6.6, P = 0.051) and a reduced MCA pulsatility index (all infections: 2.6, 1.2–5.3, P = 0.012; sub-microscopic infections: 2.8, 1.1–7.5, P = 0.035). Sub-microscopic P. falciparum infections were additionally associated with a reduced cerebroplacental ratio (3.64, 1.22–10.88, P = 0.021). There were too few P. vivax infections to draw robust conclusions. An increased UA resistance index was associated with histological evidence of placental malaria (5.1, 2.3–10.9, P < 0.001; sensitivity 0.26, specificity 0.93). A low cerebroplacental Doppler ratio was associated with concurrently measuring small-for-gestational-age, and with low birth weight.

Discussion/conclusion

Both microscopic and sub-microscopic P. falciparum infections impair fetoplacental and intrafetal flow, at least temporarily. Increased UA resistance has high specificity but low sensitivity for the detection of placental infection. These findings suggest that interventions to protect the fetus should clear and prevent both microscopic and sub-microscopic malarial infections.

Trial Registration ClinicalTrials.gov NCT01136850. Registered 06 April 2010

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-017-1689-z) contains supplementary material, which is available to authorized users.

Racial/ethnic standards for fetal growth: the NICHD Fetal Growth Studies

OBJECTIVE

Fetal growth is associated with long-term health yet no appropriate standards exist for the early identification of undergrown or overgrown fetuses. We sought to develop contemporary fetal growth standards for 4 self-identified US racial/ethnic groups.

STUDY DESIGN

We recruited for prospective follow-up 2334 healthy women with low-risk, singleton pregnancies from 12 community and perinatal centers from July 2009 through January 2013. The cohort comprised: 614 (26%) non-Hispanic whites, 611 (26%) non-Hispanic blacks, 649 (28%) Hispanics, and 460 (20%) Asians. Women were screened at 8w0d to 13w6d for maternal health status associated with presumably normal fetal growth (aged 18-40 years; body mass index 19.0-29.9 kg/m(2); healthy lifestyles and living conditions; low-risk medical and obstetrical history); 92% of recruited women completed the protocol. Women were randomized among 4 ultrasonography schedules for longitudinal fetal measurement using the Voluson E8 (GE Healthcare, Milwaukee, WI). In-person interviews and anthropometric assessments were conducted at each visit; medical records were abstracted. The fetuses of 1737 (74%) women continued to be low risk (uncomplicated pregnancy, absent anomalies) at birth, and their measurements were included in the standards. Racial/ethnic-specific fetal growth curves were estimated using linear mixed models with cubic splines. Estimated fetal weight (EFW) and biometric parameter percentiles (5th, 50th, 95th) were determined for each gestational week and comparisons made by race/ethnicity, with and without adjustment for maternal and sociodemographic factors.

RESULTS

EFW differed significantly by race/ethnicity >20 weeks. Specifically at 39 weeks, the 5th, 50th, and 95th percentiles were 2790, 3505, and 4402 g for white; 2633, 3336, and 4226 g for Hispanic; 2621, 3270, and 4078 g for Asian; and 2622, 3260, and 4053 g for black women (adjusted global P < .001). For individual parameters, racial/ethnic differences by order of detection were: humerus and femur lengths (10 weeks), abdominal circumference (16 weeks), head circumference (21 weeks), and biparietal diameter (27 weeks). The study-derived standard based solely on the white group erroneously classifies as much as 15% of non-white fetuses as growth restricted (EFW <5th percentile).

CONCLUSION

Significant differences in fetal growth were found among the 4 groups. Racial/ethnic-specific standards improve the precision in evaluating fetal growth.

Azithromycin-containing intermittent preventive treatment in pregnancy affects gestational weight gain, an important predictor of birthweight in Papua New Guinea - an exploratory analysis

In Papua New Guinea, intermittent preventive treatment with sulphadoxine-pyrimethamine and azithromycin (SPAZ-IPTp) increased birthweight despite limited impact on malaria and sexually transmitted infections. To explore possible nutrition-related mechanisms, we evaluated associations between gestational weight gain (GWG), enrolment body mass index (BMI) and mid-upper arm circumference (MUAC), and birthweight. We investigated whether the increase in birthweight associated with SPAZ-IPTp may partly be driven by a treatment effect on GWG. The mean GWG rate was 393 g/week (SD 250; n = 948). A 100 g/week increase in GWG was associated with a 14 g (95% CI 2.6, 25.4) increase in birthweight (P = 0.016). Enrolment BMI and MUAC also positively correlated with birthweight. SPAZ-IPTp was associated with increased GWG [58 g/week (26, 900), P < 0.001, n = 948] and with increased birthweight [48 g, 95% CI (8, 880), P = 0.019] when all eligible women were considered (n = 1947). Inclusion of GWG reduced the birthweight coefficient associated with SPAZ-IPTp by 18% from 44 to 36 g (n = 948), although SPAZ-IPTp was not significantly associated with birthweight among women for whom GWG data were available (P = 0.13, n = 948). One month post-partum, fewer women who had received SPAZ-IPTp had a low post-partum BMI (<18.5 kg m(-2) ) [adjusted risk ratio: 0.55 (95% CI 0.36, 0.82), P = 0.004] and their babies had a reduced risk of wasting [risk ratio 0.39 (95% CI 0.21, 0.72), P = 0.003]. SPAZ-IPTp increased GWG, which could explain its impact on birthweight and maternal post-partum BMI. Future trials of SPAZ-IPTp must incorporate detailed anthropometric evaluations to investigate mechanisms of effects on maternal and child health.

Preterm or not--an evaluation of estimates of gestational age in a cohort of women from Rural Papua New Guinea

BACKGROUND

Knowledge of accurate gestational age is required for comprehensive pregnancy care and is an essential component of research evaluating causes of preterm birth. In industrialised countries gestational age is determined with the help of fetal biometry in early pregnancy. Lack of ultrasound and late presentation to antenatal clinic limits this practice in low-resource settings. Instead, clinical estimators of gestational age are used, but their accuracy remains a matter of debate.

METHODS

In a cohort of 688 singleton pregnancies from rural Papua New Guinea, delivery gestational age was calculated from Ballard score, last menstrual period, symphysis-pubis fundal height at first visit and quickening as well as mid- and late pregnancy fetal biometry. Published models using sequential fundal height measurements and corrected last menstrual period to estimate gestational age were also tested. Novel linear models that combined clinical measurements for gestational age estimation were developed. Predictions were compared with the reference early pregnancy ultrasound (<25 gestational weeks) using correlation, regression and Bland-Altman analyses and ranked for their capability to predict preterm birth using the harmonic mean of recall and precision (F-measure).

RESULTS

Average bias between reference ultrasound and clinical methods ranged from 0-11 days (95% confidence levels: 14-42 days). Preterm birth was best predicted by mid-pregnancy ultrasound (F-measure: 0.72), and neuromuscular Ballard score provided the least reliable preterm birth prediction (F-measure: 0.17). The best clinical methods to predict gestational age and preterm birth were last menstrual period and fundal height (F-measures 0.35). A linear model combining both measures improved prediction of preterm birth (F-measure: 0.58).

CONCLUSIONS

Estimation of gestational age without ultrasound is prone to significant error. In the absence of ultrasound facilities, last menstrual period and fundal height are among the more reliable clinical measures. This study underlines the importance of strengthening ultrasound facilities and developing novel ways to estimate gestational age.