Fetal lung maturity in pregnancies complicated by insulin-dependent and gestational diabetes: a matched cohort study

Diabetes in pregnancy and lung health in offspring: developmental origins of respiratory disease

Diabetes is an increasingly common complication of pregnancy. In parallel with this trend, a rise in chronic lung disease in children has been observed in recent decades. While several adverse health outcomes associated with exposure to diabetes in utero have been documented in epidemiological and experimental studies, few have examined the impact of diabetes in pregnancy on offspring lung health and respiratory disease. We provide a comprehensive overview of current literature on this topic, finding suggestive evidence that exposure to diabetes in utero may have adverse effects on lung development. Delayed lung maturation and increased risk of respiratory distress syndrome have been consistently observed among infants born to mothers with diabetes and these findings are also observed in some rodent models of diabetes in pregnancy. Further research is needed to confirm and characterize epidemiologic observations that diabetes in pregnancy may predispose offspring to childhood wheezing illness and asthma. Parallel translational studies in human pregnancy cohorts and experimental models are needed to explore the role of fetal programming and other potential biological mechanisms in this context.

Consequences of a Maternal High-Fat Diet and Late Gestation Diabetes on the Developing Rat Lung

Rationale

Infants born to diabetic or obese mothers are at risk of respiratory distress and persistent pulmonary hypertension of the newborn (PPHN), conceivably through fuel-mediated pathogenic mechanisms. Prior research and preventative measures focus on controlling maternal hyperglycemia, but growing evidence suggests a role for additional circulating fuels including lipids. Little is known about the individual or additive effects of a maternal high-fat diet on fetal lung development.

Objective

The objective of this study was to determine the effects of a maternal high-fat diet, alone and alongside late-gestation diabetes, on lung alveologenesis and vasculogenesis, as well as to ascertain if consequences persist beyond the perinatal period.

Methods

A rat model was used to study lung development in offspring from control, diabetes-exposed, high-fat diet-exposed and combination-exposed pregnancies via morphometric, histologic (alveolarization and vasculogenesis) and physiologic (echocardiography, pulmonary function) analyses at birth and 3 weeks of age. Outcomes were interrogated for diet, diabetes and interaction effect using ANOVA with significance set at p≤0.05. Findings prompted additional mechanistic inquiry of key molecular pathways.

Results

Offspring exposed to maternal diabetes or high-fat diet, alone and in combination, had smaller lungs and larger hearts at birth. High-fat diet-exposed, but not diabetes-exposed offspring, had a higher perinatal death rate and echocardiographic evidence of PPHN at birth. Alveolar mean linear intercept, septal thickness, and airspace area (D₂) were not significantly different between the groups; however, markers of lung maturity were. Both diabetes-exposed and diet-exposed offspring expressed more T1α protein, a marker of type I cells. Diet-exposed newborn pups expressed less surfactant protein B and had fewer pulmonary vessels enumerated. Mechanistic inquiry revealed alterations in AKT activation, higher endothelin-1 expression, and an impaired Txnip/VEGF pathway that are important for vessel growth and migration. After 3 weeks, mortality remained highest and static lung compliance and hysteresis were lowest in combination-exposed offspring.

Conclusion

This study emphasizes the effects of a maternal high-fat diet, especially alongside late-gestation diabetes, on pulmonary vasculogenesis, demonstrates adverse consequences beyond the perinatal period and directs attention to mechanistic pathways of interest. Findings provide a foundation for additional investigation of preventative and therapeutic strategies aimed at decreasing pulmonary morbidity in at-risk infants.

Changes in diabetes status between pregnancies and impact on subsequent newborn outcomes

OBJECTIVE

Pregnancies complicated by gestational diabetes mellitus (GDM) or preexisting diabetes mellitus (DM) are at high risk for adverse newborn outcomes. Whether GDM history, recurrence, or transition to DM modifies such risks is unknown.

STUDY DESIGN

Medical record data on 62,013 repeat singleton pregnancies were collected retrospectively from women who delivered at least twice in Utah (2002 through 2010). Poisson regression models with robust variance estimators were used to estimate relative risks (RR) and 95% confidence intervals (CI) associated with GDM/DM status at the previous and/or current pregnancy relative to those without GDM/DM at either. Large for gestational age (LGA), shoulder dystocia, preterm birth (<37 weeks), respiratory distress syndrome, and other neonatal morbidities were examined adjusting for study site, maternal age, race, parity, interpregnancy interval, prepregnancy body mass index, and smoking status.

RESULTS

GDM in the previous pregnancy alone increased the risk of LGA in the current pregnancy (RR, 1.20; 95% CI, 1.05-1.38). Recurrent GDM increased the risks of LGA (RR, 1.76; 95% CI, 1.56-1.98), shoulder dystocia (RR, 1.98; 95% CI, 1.46-2.70), and preterm birth (RR, 1.68; 95% CI, 1.44-1.96) beyond that observed for pregnancies with current GDM alone. Women with GDM in a previous pregnancy that transitioned to DM in the current pregnancy and women with DM prior to the previous pregnancy had increased risks of all above outcomes.

CONCLUSION

GDM in a previous pregnancy alone without recurrence may still confer an increased LGA risk. Pregnancies complicated by GDM that transition to DM and those with DM prior to the previous pregnancy have the highest risks of adverse newborn outcomes.

Neonatal functional lung maturity relative to gestational age at delivery, fetal growth, and pregnancy characteristics in triplet births

OBJECTIVE

The purpose of this study was to determine if functional lung maturity (FtLM) of triplets was affected by differentiating factors within the triplet set.

METHODS

This was a retrospective cohort study of triplets. Data were collected on maternal, pregnancy and neonatal characteristics and FtLM was determined, based on selected neonatal outcomes.

RESULTS

Functional lung immaturity (FtLI) was found in 35.5% of the infants and occurred in those born between 28.1 and 34.6 weeks gestation. Gestational age at delivery, pre-pregnancy BMI, and gestational diabetes were predictive of an infant having FtLM; while infertility treatment, pre-pregnancy BMI, and preeclampsia were predictors of FtLM discordance.

CONCLUSIONS

Our results demonstrated FtLI was likely at early gestation (<28 weeks) and FtLM was probable beyond 35 weeks. Discordance for FtLM was likely at 32 weeks; therefore, clinicians should guard against complacency that this gestational mark assures an uncomplicated respiratory course for all infants within the set.

Amniotic lamellar body counts determined with the Sysmex XE-2100 analyzer to predict fetal lung maturity during diabetic and other complicated pregnancies

OBJECTIVE

The detection of amniotic lamellar bodies (LB) has been shown to be a rapid and simple way to assess fetal lung maturity (FLM). The maturity thresholds for LB vary due to different factors, one being the type of particle-count analyser used.

MATERIAL AND METHODS

The Sysmex XE-2100 hematological analyser was evaluated in determination of amniotic LB counts and compared with lecithin/sphingomyelin (L/S) and phosphatidylglycerol (PG) determination. We analysed 132 amniotic samples from a total of 109 mothers (71 diabetic) with 112 infants. Results. The correlation between the LB counts obtained with the Sysmex XE-2100 and our reference thin layer chromatography (TLC) phospholipid method was good. Samples with low L/S ratio (< or = 2.0) and no PG (i.e. premature fetal lung status), had low LB counts (n = 18, mean 8500/L, range 1000-26000), whereas 51 samples with mature fetal lung status had high LB counts (mean 63600/uL, range 20,000-139,000). In all our four cases of respiratory distress syndrome the LB counts were low (range 1000-28000/uL). The reference values for FLM determination were established: < or = 6000/microL for immature, values between 7000 and 35,000/uL for borderline results and >35,000/uL for mature. CONCLUSIONS. The amniotic LB count analysis with Sysmex XE-2100 has many advantages being a repeatable, inexpensive and quantitative method with a very short turn-around time. Consequently, our routine is to perform LB counts initially from all amniotic samples and only borderline LB results are analysed with TLC.

Pictorial Essay: Infants of diabetic mothers

About 3 to 10% of pregnancies are complicated by glycemic control abnormalities. Maternal diabetes results in significantly greater risk for antenatal, perinatal, and neonatal morbidity and mortality, as well as congenital malformations. The number of diabetic mothers is expected to rise, as more and more of the obese pediatric female population in developed and some developing countries progresses to childbearing age. Radiologists, being part of the teams managing such pregnancies, should be well aware of the findings that may be encountered in infants of diabetic mothers. Timely, accurate, and proper radiological evaluation can reduce morbidity and mortality in these infants. The purpose of this essay is to illustrate the imaging findings in the various pathological conditions involving the major body systems in the offspring of women with diabetes.

The effect of clinical characteristics on the lecithin/sphingomyelin ratio and lamellar body count: a cross-sectional study

OBJECTIVES

To study the changes in the lecithin/sphingomyelin (L/S) ratio and lamellar body count (LBC) during pregnancy and to study the effect of clinical characteristics on these measurements.

METHODS

We reviewed in retrospect the amniotic fluid samples for the assessment of fetal lung maturity of consecutive women between January 1996 and December 2000. We evaluated the effect of antenatal administration of glucocorticoids, the presence of diabetes, fetal growth restriction and the amount of amniotic fluid on the L/S ratio and LBC. We then constructed normal curves, by relating the L/S ratio and LBC to gestational age in the cases without respiratory distress syndrome (RDS). Data from the literature were added to these curves.

RESULTS

From the 334 included women, 64 infants (19%) developed RDS. The LBC was lower in women with polyhydramnios (p = 0.04), and similar in women with oligohydramnios. Administration of glucocorticoids, the presence of maternal diabetes or fetal growth restriction did not affect the L/S ratio or the LBC. The median L/S ratio in cases without RDS showed a constant increase from a gestational age of 28 weeks onwards. The median LBC increased slowly between a gestational age of 28 weeks and 34 weeks, to increase more steeply thereafter.

CONCLUSIONS

The amount of amniotic fluid affects the LBC, but not the L/S ratio. Since the L/S ratio and the LBC increase with gestation, differences in gestational age should be taken into account in the interpretation of these fetal lung maturity tests.

TYPE 1 DIABETES IN PREGNANCY; INFLUENCES ON MOTHER AND FETUS

Type 1 diabetes complicates around 1 in 200 to 300 pregnancies in the United Kingdom. Historically maternal type 1 diabetes carried very high risks for mother and child. Introduction of insulin led to an immediate, marked decline in the previously very high rates of maternal mortality; in contrast an improvement in perinatal outcomes occurred more slowly but was nevertheless dramatic. This is strikingly demonstrated by the temporal decline in perinatal mortality in offspring of mothers with type 1 diabetes which was virtually universal before use of insulin in the 1920's, likely remained in excess of 20% even in the 1960's and fell to under 4% by the 1990's. The reasons for this more gradual improvement in perinatal outcomes cannot be defined with precision but will have been influenced by improved glycaemic management with use of intensive, multiple dose insulin treatment and home glucose monitoring; improvements in obstetric and neonatal management, and better management of complications of diabetes before and during pregnancy. In 1989 the St Vincent declaration proposed that pregnancy outcomes in women with type 1 diabetes should approximate those of the non-diabetic population. While the long term improvements in fetal outcomes have been dramatic, contemporary surveys confirm a persistent doubling or more of rates of congenital anomaly and a three to four fold increase in perinatal mortality in the UK and other European countries which will require further clinical innovation to overcome.

Anthropometric Parameters in Infants of Gestational Diabetic Women With Strict Glycemic Control

OBJECTIVE

Differences in weight and body composition have been reported between infants of nondiabetic and diabetic mothers. These differences may explain the propensity for shoulder dystocia in the diabetic population. We investigated whether differences in anthropometric measurements still exist between infants of nondiabetic and diabetic mothers following strict glycemic control.

METHODS

This was a prospective cohort study. The study group included infants of well-controlled gestational diabetic mothers (mean capillary glucose less than 100 mg/dL). Controls were infants of nondiabetic mothers matched for gender, gestational age, ethnicity, and birth weight. Only singleton term pregnancies were included. Both groups were studied within 24 hours of delivery. The following measurements were obtained: birth weight, infant length, femur length, head, chest, abdomen and thigh circumferences, and biacromial distance. Student t tests were used to compare the measured parameters between groups. P < .05 was considered significant. A sample size of 63 subjects in each group was needed to demonstrate a difference of 0.5 cm (+/- 1.0 cm) of the biacromial distance between the 2 groups, which we considered clinically significant, with a probability of 95% and power of 80%.

RESULTS

Sixty seven infants in each group were included in the study. Anthropometric measurements did not differ significantly between the groups. We did a secondary analysis on neonates who weighed 4,000 g or more at birth. Anthropometric measurements again did not differ significantly between the groups.

CONCLUSION

Anthropometric measurements of infants of mothers with well-controlled gestational diabetes do not differ from infants of nondiabetic mothers.

LEVEL OF EVIDENCE

II-2.

The controversy surrounding fetal lung maturity in diabetes in pregnancy: a re-evaluation

It is beyond the scope of this article to discuss the biochemical markers of fetal lung maturity and their pathophysiological characteristics. This information can be found in several textbooks and review articles. Instead, this article addresses controversial issues that confront the obstetrician in daily clinical practice related to the role of diabetes (glucose) as the teratogen for lung morbidity, and the association between lung maturity testing results and actual lung morbidity.

A comparison of amniotic fluid fetal pulmonary phospholipids in normal and diabetic pregnancy

OBJECTIVE

Our purpose was to determine whether there are differences in the timing of the appearance of various amniotic fluid fetal pulmonary phospholipids in normal and diabetic pregnancy.

STUDY DESIGN

A case-control study of 295 subjects with diabetes and 590 control subjects was performed by use of gestational age-matched amniocentesis specimens analyzed for lecithin/sphingomyelin (L/S) ratio, phosphatidylinositol (PI), and phosphatidylglycerol (PG) composition. Diabetic subjects were stratified according to type of diabetes, degree of blood glucose control, and birth percentile of the neonate.

RESULTS

There was no difference in L/S ratios over gestational age by type of diabetes or quality of glycemic control. Women with preexisting diabetes had significantly higher PI levels at 33 to 35 weeks' gestation, which became similar to levels of control subjects after 36 weeks, whereas patients with gestational diabetes mellitus and control subjects had similar PI levels throughout. In diabetic subjects, the onset of production of PG was delayed from 35.9 +/- 1.1 weeks (controls) to 38.7 +/- 0.9 weeks (overt diabetics) and 37.3 +/- 1.0 weeks for gestational diabetes mellitus (P <.001). The delay in PG synthesis was not related to infant sex, level of maternal glucose control, or fetal macrosomia.

CONCLUSIONS

Fetal pulmonary maturation, as evidenced by the onset of PG production in the amniotic fluid, is delayed in diabetic pregnancy by 1 to 1.5 weeks. This delay appears to be associated with an early and sustained elevation in amniotic fluid PI levels at 32 to 34 weeks.