Maternal and perinatal outcomes amongst haemoglobinopathy carriers: a systematic review

Management of the Sickle Cell Trait: An Opinion by Expert Panel Members

The number of individuals with the sickle cell trait exceeds 300 million worldwide, making sickle cell disease one of the most common monogenetic diseases globally. Because of the high frequency of sickle cell disease, reproductive counseling is of crucial importance. In addition, unlike other carrier states, Sickle Cell Trait (SCT) seems to be a risk factor for several clinical complications, such as extreme exertional injury, chronic kidney disease, and complications during pregnancy and surgery. This expert panel believes that increasing knowledge about these clinical manifestations and their prevention and management can be a useful tool for all healthcare providers involved in this issue.

Pregnancy outcomes among women affected with thalassemia traits

OBJECTIVE

To compare the maternal and perinatal outcomes between a group of pregnant women diagnosed with thalassemia traits and normal controls.

STUDY DESIGN

A retrospective cohort study was conducted on singleton pregnant women affected and unaffected by thalassemia traits who attended an antenatal care clinic and delivered in Siriraj Hospital. Thalassemia status for all subjects was diagnosed by hemoglobin typing and/or DNA analysis. Patient charts were reviewed from January 2007 to December 2018. The control participants were randomly selected from the same period, with a control-case ratio of around 1:1.

RESULTS

Overall, 1288 women with thalassemia traits (348 with α thal-1 trait, 424 with β thal trait and 516 with HbE trait) and 1305 women in the control group were recruited. Baseline characteristics of both groups were similar, with the exception that the hematocrit level in the first trimester in the thalassemia trait group was significantly lower than that in the control group (34.8 ± 3.4% VS 36.9 ± 3.0%; p < 0.001). The prevalence of pregnancy-induced hypertension (PIH) was higher in the thalassemia trait group, at 6.9% VS 4.7% in the control group; p = 0.018. When subgroups were analyzed between each thalassemia trait, the number of maternal anemias in the first and third trimester was higher for all thalassemia traits compared to the normal group. The β thal and HbE traits increased the risk of PIH, with a relative risk (RR) = 1.67 and 1.66, respectively.

CONCLUSIONS

Thalassemia traits minimally but significantly increase the risk of hypertensive disorders and maternal anemia. In addition, physiological changes during pregnancy may worsen the severity of anemia in the pregnant women with thalassemia traits.

Pregnancy outcomes in women with a hemoglobinopathy trait: a multicenter, retrospective study

Purpose

To determine the risk of adverse maternal and neonatal outcomes in pregnant women with a hemoglobinopathy trait.

Materials and methods

Retrospective cohort study was conducted to compare adverse maternal and neonatal outcomes between pregnant women with a hemoglobinopathy trait (study group; n = 172), and without a hemoglobinopathy trait (control group; n = 360). The medical data were extracted from clinical records of pregnant women attending antenatal care and delivering at the University Hospital Basel or University Hospital Zurich between 2015 and 2018.

Results

A total of 172 pregnant women with a hemoglobinopathy trait and 360 controls were recruited. Apart from fetal acidosis, the groups did not differ significantly in any variables of adverse neonatal outcomes. Whereas, among the maternal outcomes the rate of abortion, gestational diabetes mellitus, bacteriuria or urinary tract infection, intrahepatic cholestasis, abnormal placentation and anemia postpartum were significantly increased in women with a hemoglobinopathy trait.

Conclusion

In our study, a hemoglobinopathy trait increased the risk of adverse maternal outcomes but did not increase adverse neonatal outcomes.

The Risk of Pregnancy Related Hypertension Disorder Associated with Sickle Cell Trait in U.S. Service Women

INTRODUCTION

The health impact of the heterozygous (Hb Ss) Sickle Cell Trait (SCT) among the estimated one million females of reproductive age in the United States on pregnancy related hypertensive disorders (PRHD) including preeclampsia is not as well understood or researched as Sickle Cell Disease (SCD).

MATERIALS AND METHODS

This retrospective cohort study included 25,020 U.S. enlisted, active duty service women during 1992 to 2013. Race within the sample is primarily black (84%) given that blacks have the highest prevalence of SCT. All 5,004 SCT positive individuals and a matched sample of 20,016 from those considered SCT negative were followed while on active duty for PRHD outcomes including gestational hypertension (GHTN), preeclampsia and eclampsia.

RESULTS

The adjusted incidence rate ratio (IRR) for any PRHD in SCT positive compared to negative individuals was 1.46 (95% CI 1.32 - 1.62). SCT positive versus negative subjects had higher health care utilization rates and utilization rate ratios (URR) for all PRHD diagnoses combined 2.03 (95%CI: 1.97 - 2.10) and for each specific PHRD diagnosis. The prevalence of preeclampsia or eclampsia did not vary by SCT status. The overall PRHD attributable risk due to SCT was 30.4% (95% CI 23.1-37.1%) and the overall number needed to screen to detect a case of PRHD was 156 (95% CI 117-220).

CONCLUSIONS

The results of this study indicate that being SCT positive is a risk factor for PRHD and provides evidence that SCT status may have an adverse effect on reproductive health. Future research needs to include other known risk factors for PRHD to include gravity and parity history, BMI, past history of PRHD prior to enlistment as well as to examine the association with maternal/child pregnancy outcomes.

Pregnancy in sickle cell trait: what we do and don't know

Sickle cell trait (SCT) is the carrier state for sickle cell disease that results from the HBB rs334 missense mutation (p.Glu6Val) in the β-globin chain of haemoglobin. While not associated with any impact on life expectancy, it has been established that SCT is associated with an increased risk of both venous thromboembolism (and in particular, pulmonary embolism) and chronic kidney disease. It is largely unknown what short- or long-term effect, if any, pregnancy has upon the risk or outcomes of these disorders. In addition, SCT has been linked with various adverse outcomes in pregnancy, ranging from maternal complications such as elevated risk of bacteriuria to potentially life-threatening entities such as pre-eclampsia and prematurity. In these scenarios also, no clear association with SCT has been established. Given the high worldwide prevalence of SCT, further studies addressing these issues are warranted.

Experiences of a High-Risk Population with Prenatal Hemoglobinopathy Carrier Screening in a Primary Care Setting: a Qualitative Study

Carrier screening for hemoglobinopathies (HbPs; sickle cell disease and thalassemia) aims to facilitate autonomous reproductive decision-making. In the absence of a Dutch national HbP carrier screening program, some primary care midwives offer screening on an ad hoc basis. This qualitative descriptive study explores how pregnant women perceive an offer of HbP carrier screening by their midwife. Semi-structured interviews (n = 26) were conducted with pregnant women at risk of being a HbP carrier, and whom were offered screening at their booking appointment in one of two midwifery practices in Amsterdam. The results showed that half of the respondents were familiar with HbPs. Generally, women perceived the offer of HbP carrier screening as positive, and most women (n = 19) accepted screening. Seven declined, of whom two already knew their carrier status. Important reasons to accept screening were to obtain knowledge about their own carrier status and health of their unborn child, and the ease of the procedure. A multistep process of decision-making was observed, as many women did not give follow-up testing (e.g. partner, invasive diagnostics) much consideration while deciding on accepting or declining HbP screening. Women experienced information overload, and preferred receiving the information at a different moment (e.g. before the intake by a leaflet, or preconceptionally). In conclusion, while prenatal HbP carrier screening is perceived as positive, informed decision-making seems to be suboptimal, and both the content and timing of the information provided needs improvement.

A retrospective comparison of pregnancy outcomes between women with alpha-thalassaemia 1 trait and normal controls

The objective of this retrospective cohort study was to compare pregnancy outcomes between low-risk pregnant women with alpha-thalassaemia-1 trait and normal controls. The database of the Maternal-Foetal Medicine unit was used to identify low-risk singleton pregnant women complicated by alpha-thalassaemia-1 trait who gave birth between January 2002 and October 2014. The low-risk pregnancies with non-carrier status for thalassaemia were assigned into the control group, with a control-to-case ratio of 10:1. During the study period, 595 women with alpha-thalassaemia-1 trait and 5950 normal controls were identified. There was no significant difference in the incidence of preterm birth and most obstetric outcomes between the two groups. However, a statistically significant difference was detected between them in terms of gestational age at delivery, 37.76 ± 2.81 vs. 38.11 ± 2.50 weeks (p = .001), birth weight, 2876 ± 581 vs. 2948 ± 527 g (p = .002) as well as the rate of low-birth weight, 17.1 vs. 12.8% (p = .002). In conclusion, this study provides new insights that alpha-thalassaemia-1 trait has minimal effect on gestational age at delivery and low-birth weight whereas other common adverse pregnancy outcomes are not increased. Impact statement What is already known on this subject: Thalassaemia trait is associated with some degree of anaemia. What the results of this study add: The prevalence of common adverse outcomes such as preterm birth, stillbirth, low Apgar scores and pregnancy-induced hypertension were not significantly different between both the groups, possibly caused by too small sample size to gain enough power. However, the rate of low-birth weight was significantly increased among pregnancy with alpha-thalassaemia-1 trait. What the implications are of these findings for clinical practice and/or further research: The information may be provided for alpha thalassaemia-1 trait mothers and their families. Physicians should guard against the occurrence of adverse pregnancy in these mothers. Prospective control study should be conducted to overcome the limitation of retrospective nature.

Pregnancy Outcomes Among Women with Homozygous Hemoglobin E Disease: A Retrospective Cohort Study

Background Homozygous hemoglobin E (HbE) disease is common, especially in Southeast Asia where the prevalence may be as high as nearly 1 % of pregnancies and it is usually associated with mild anemia. Nevertheless, the effects of the disease on pregnancy outcomes have never been explored. Objective To compare the obstetric adverse outcomes between singleton pregnancies complicated with HbE disease and normal controls. Patients and Methods A retrospective cohort study was undertaken by assessment of the database of maternal-fetal medicine units, Chiang Mai University, Thailand, from January 2000 to December 2014 to search for the records of pregnant women complicated by the disease. The records of low risk pregnancies were randomly selected as a control group with a ratio of 10:1. Pregnancies with underlying medical diseases or fetal abnormalities as well as those with no complete data were excluded. Result During the study period, 78 women with homozygous HbE disease (study group) and 780 normal controls were recruited. Most baseline characteristics of the two groups were similar. The mean birth weight was significantly lower in the study group (2683 ± 627 vs 2925 ± 623 g, P = 0.001).The prevalence of fetal growth restriction was also significantly higher in the study group (13.2 vs 6.7 %, P = 0.040, relative risk 1.96; 95 % CI 1.04-3.69), whereas the rates of other outcomes such as preterm birth were comparable. Conclusion for Practice Homozygous HbE disease does not increase risk of common adverse pregnancy outcomes, but it significantly increases risk of fetal growth restriction, resulting in significantly lower mean birth weight.

Incidence and Risks of Congenital Anomalies of Kidney and Urinary Tract in Newborns: A Population-Based Case-Control Study in Taiwan

Congenital anomalies of the kidney and urinary tract (CAKUT) are 1 of the major factors in young adults needing renal replacement therapy, but there is little extensive assessment of their incidence and risk factors. This study aimed to evaluate trends in the incidence of and risk factors for CAKUT among all births in Taiwan.This population-based case-control study design was conducted using the Taiwan national births registry, which contains detailed information about maternal health and characteristics of newborns, supplied by health professionals. Of 1,603,794 newborns registered between 2004 and 2014, 668 infants were reported to have CAKUT. Newborns without congenital anomalies were matched with CAKUT cases by birth year, month, and Apgar score in a ratio of 5:1. Odds ratio (OR) and 95% confidence interval (CI) for developing CAKUT were calculated using a conditional multivariate logistic regression model.The incidence of CAKUT was approximately 4.2 per 10,000 births. The adjusted ORs for CAKUT in newborns associated with maternal age of 20 to 29 (OR, 2.18; 95% CI, 1.11-4.28), or 30 to 39 (OR, 2.29; 95% CI, 1.17-4.51), maternal gestational diabetes (OR, 2.22, 95% CI, 1.06-4.67), maternal thalassemia/hemochromatosis (OR, 2.67; 95% CI, 1.35-5.27), polyhydramnios or oligohydramnios (OR, 9.16; 95% CI, 5.46-15.37), birth parity >1 (OR, 0.27; 95% CI, 0.15-0.50), having a gestational age <37 weeks (OR, 1.48; 95% CI, 1.23-1.78), and being a boy (OR, 1.83; 95% CI, 1.53-2.19). Infants of mother with gestational diabetes were more likely to have congenital anomalies, small gestational age (<37 weeks) and low birth weight.CAKUT are associated with several maternal health risk factors. As Taiwan has the highest prevalence and incidence rates of end-stage renal disease in the world, these findings strongly support the need to develop professional guidelines for prenatal counseling and management of women at risk of adverse birth outcomes, to prevent kidney disease progression and reduce complications.

Urinary Bladder Dysfunction in Transgenic Sickle Cell Disease Mice

Background

Urological complications associated with sickle cell disease (SCD), include nocturia, enuresis, urinary infections and urinary incontinence. However, scientific evidence to ascertain the underlying cause of the lower urinary tract symptoms in SCD is lacking.

Objective

Thus, the aim of this study was to evaluate urinary function, in vivo and ex vivo, in the Berkeley SCD murine model (SS).

Methods

Urine output was measured in metabolic cage for both wild type and SS mice (25-30 g). Bladder strips and urethra rings were dissected free and mounted in organ baths. In isolated detrusor smooth muscle (DSM), relaxant response to mirabegron and isoproterenol (1nM-10μM) and contractile response to (carbachol (CCh; 1 nM-100μM), KCl (1 mM-300mM), CaCl₂ (1μM-100mM), α,β-methylene ATP (1, 3 and 10 μM) and electrical field stimulation (EFS; 1-32 Hz) were measured. Phenylephrine (Phe; 10nM-100μM) was used to evaluate the contraction mechanism in the urethra rings. Cystometry and histomorphometry were also performed in the urinary bladder.

Results

SS mice present a reduced urine output and incapacity to produce typical bladder contractions and bladder emptying (ex vivo), compared to control animals. In DSM, relaxation in response to a selective β3-adrenergic agonist (mirabegron) and to a non-selective β-adrenergic (isoproterenol) agonist were lower in SS mice. Additionally, carbachol, α, β-methylene ATP, KCl, extracellular Ca²⁺ and electrical-field stimulation promoted smaller bladder contractions in SS group. Urethra contraction induced by phenylephrine was markedly reduced in SS mice. Histological analyses of SS mice bladder revealed severe structural abnormalities, such as reductions in detrusor thickness and bladder volume, and cell infiltration.

Conclusions

Taken together, our data demonstrate, for the first time, that SS mice display features of urinary bladder dysfunction, leading to impairment in urinary continence, which may have an important role in the pathogenesis of the enuresis and infections observed the SCD patients.

Pregnancy outcomes among women with hemoglobin E trait

OBJECTIVE

To compare the maternal and fetal outcomes between pregnant women complicated with hemoglobin E (HbE) trait and normal controls.

PATIENTS AND METHODS

A retrospective cohort study was conducted by assessment of the database of maternal-fetal medicine units from January 2003 to December 2013 to identify singleton pregnant women complicated by HbE trait. Pregnancies with medical complications or fetal anomalies were excluded. The normal controls were low-risk pregnancies and were non-carrier status for thalassemia and hemoglobinopathy.

RESULT

During the study period, 1073 women with HbE trait and 2146 normal controls were included. The baseline characteristics of the two groups were comparable except that the number of prenatal visit was statistically higher in study group (8.55 ± 3.03 versus 7.85 ± 4.33, p = <0.001). Most pregnancy outcomes were not significantly different. However, the rate of asymptomatic bacteriuria was minimally higher in the study group, 3.5% versus 2.3%; p = 0.042 (relative risk 1.19; 95%CI: 0.98-1.43). Note that the rates of gestational diabetes tend to be higher in the group of HbE trait (7.6% versus 6.8%), but did not reach a statistical level.

CONCLUSION

The HbE trait does not significantly increase risk of common adverse pregnancy outcomes, except for minimal increase in asymptomatic bacteriuria.

Pregnancy outcomes amongst thalassemia traits

Objective

To compare the pregnancy outcome between pregnancies affected and not affected by thalassemia trait.

Methods

A retrospective case–control cohort study was conducted on singleton pregnant women who attended antenatal care and delivered at Songklanagarind Hospital. All of the participating thalassemia trait pregnant women were diagnosed based on hemoglobin typing and/or DNA analysis. A ratio of around 1–1 was used to compare their pregnancy outcomes with normal pregnant women.

Results

Seven hundred thirty-nine thalassemia trait and 799 normal pregnant women were included in the study. All of the women were Thai nationals living in the Southern Region of Thailand and nearly all of them had spontaneously conceived. Maternal complication rates of gestational diabetes, preterm birth, antepartum bleeding, postpartum bleeding, shoulder dystocia and puerperal morbidity, and the rates of neonatal complications: macrosomia, fetal weight <2,000 g, intrauterine growth restriction (IUGR), stillbirth, low Apgar score (<7) at 1 and 5 min and NICU admission, were not significantly different between the two groups. The rate of pre-eclampsia, however, was significantly different, with RRs of 1.73 (CI 1.01–3.00).

Conclusion

The thalassemia trait condition did not affect the risk of gestational diabetes, postpartum hemorrhage, stillbirth, preterm birth and puerperal morbidity. However, pre-eclampsia should be warranted especially among nulliparous and high-BMI pregnant women.