Delineation of a multiple congenital abnormality syndrome in the offspring of pregnant women affected with high fever-related disorders: a population-based study

Update on the gestational effects of maternal hyperthermia

OBJECTIVES

I plan to review the types of defects caused by gestational hyperthermia. Hyperthermia-induced malformations in animals and humans involve many organs and structures, particularly the central nervous system, as well as other defects. The type of defect is related to the timing of the hyperthermic insult, and the underlying mechanisms include cell death, membrane disruption, vascular disruption, and placental infarction.

METHODS

Review of recent epidemiologic studies (2005-2020) has confirmed an association between gestational hyperthermia and birth defects.

RESULTS

There are strong associations between neural tube defects and maternal fever, and other studies have demonstrated associations between first trimester hyperthermia and an increased risk for cardiovascular defects, oral clefts, isolated congenital ear defects, cataracts, hypospadias, renal anomalies, possibly anorectal malformations, and congenital anomalies in general, suggesting that this association between maternal hyperthermia and birth defects in humans is causal. The first prospective evaluation of maternal fever was reported in 1998, and this study confirmed findings from previous case-control studies and case series regarding the magnitude and duration of elevated maternal body temperature in relation to an increased risk for neural tube defects as well as a specific pattern of malformation.

CONCLUSIONS

The consistency of findings across these different study designs supports the causal nature of the relationship between maternal fever and specific birth defects. This review summarizes the recent human evidence documenting the gestational effects of maternal hyperthermia.

Environmental mechanisms of orofacial clefts

Orofacial clefts (OFCs) are among the most common birth defects and impart a significant burden on afflicted individuals and their families. It is increasingly understood that many nonsyndromic OFCs are a consequence of extrinsic factors, genetic susceptibilities, and interactions of the two. Therefore, understanding the environmental mechanisms of OFCs is important in the prevention of future cases. This review examines the molecular mechanisms associated with environmental factors that either protect against or increase the risk of OFCs. We focus on essential metabolic pathways, environmental signaling mechanisms, detoxification pathways, behavioral risk factors, and biological hazards that may disrupt orofacial development.

Influence of hyperthermal regimes on experimental teratoma development in vitro

We screened for the impact of hyperthermal regimes varying in the cumulative equivalent minutes at 43°C (CEM43°C) and media composition on tumour development using an original teratoma in vitro model. Rat embryos (three germ layers) were microsurgically isolated and cultivated at the air‐liquid interface. During a two week period, ectodermal, mesodermal and endodermal derivatives developed within trilaminar teratomas. Controls were grown at 37°C. Overall growth was measured, and teratoma survival and differentiation were histologically assessed. Cell proliferation was stereologically quantified by the volume density of Proliferating Cell Nuclear Antigen. Hyperthermia of 42°C, applied for 15 minutes after plating (CEM43°C 3.75 minutes), diminished cell proliferation (P ˂ .0001) and enhanced differentiation of both myotubes (P ˂ .01) and cylindrical epithelium (P ˂ .05). Hyperthermia of 43°C applied each day for 30 minutes during the first week (CEM43°C 210 minutes) impaired overall growth (P ˂ .01) and diminished cell proliferation (P ˂ .0001). Long‐term hyperthermia of 40.5°C applied for two weeks (CEM43°C 630 minutes) significantly impaired survival (P ˂ .005). Long‐term hyperthermia of 40.5°C applied from the second day when differentiation of tissues begins (CEM43°C 585 minutes) impaired survival (P ˂ .0001), overall growth (P ˂ .01) and cartilage differentiation (P ˂ .05). No teratomas survived extreme regimes: 43°C for 24 hours (CEM43°C 1440 minutes), hyperthermia in the scant serum‐free medium (CEM43°C 630 minutes) or treatment with an anti‐HSP70 antibody before long‐term hyperthermia 40.5°C from the second day (CEM43°C 585 minutes). This in vitro research provided novel insights into the impact of hyperthermia on the development of experimental teratomas from their undifferentiated sources and are thus of potential interest for future therapeutic strategies in corresponding in vivo models.

11.7 T MR Imaging Revealed Dilatation of Virchow-Robin Spaces within Hippocampus in Maternally Lipopolysaccharide-exposed Rats

PURPOSE

11.7 Tesla MRI was examined to detect Virchow-Robin spaces (VRSs) smaller than 100 μm in the rat brain. The effects of maternal exposure to lipopolysaccharide (LPS) were evaluated on basis of the number of dilated VRSs in the offspring rat brain.

METHODS

T₂-weighted MRI with an in-plane resolution up to 78 μm (repetition time = 5000 ms, echo time = 35 ms, slice thickness = 250 μm, imaging plane, coronal) was applied to identify VRSs. The dilated VRSs were counted in the rat brain at 5 and 10 weeks of age. The dams of half the number in each group were treated with LPS during pregnancy, and the remaining half was employed as control. LPS injection in gestation period was used to simulate maternal infections, the method of which was widely accepted as a rat model inducing neuropsychiatric disorders in the offspring. Effects of LPS exposure on the offspring rat brain were statistically investigated.

RESULTS

VRSs as small as 78 μm were successfully detected by the ultra high-field MRI. All dilated VRSs were observed within lacunosum molecular layer of hippocampus, and molecular and granular layers of dentate gyrus around hippocampal fissure. In juvenile rats (5 weeks of age), the number of dilated VRSs was significantly increased in the prenatal LPS exposed rat brain (12.9 ± 2.4, n = 7) than in the control (5.3 ± 1.5, n = 7, P < 0.05), while in young adult rats (10 weeks of age), there was no significant difference in the number between the prenatal LPS exposed rat brain (3.6 ± 0.9, n = 5) and the control (2.6 ± 0.4, n = 5).

CONCLUSION

The results of the present study suggested that maternal infection might cause dilatation of VRSs through neural damages especially in the dentate gyrus of the offspring rats. Thus, ultra high-field MRI can offer a promising diagnostic tool capable of determining the location of neonatal brain damage caused by maternal infections.

Prenatal Diagnosis and Postnatal Outcome of Schizencephaly

The aim of this study was to present our experience with 5 cases of fetal schizencephaly in terms of prenatal diagnostic features, and postnatal outcome. The database of prenatal diagnosis unit was searched for antenatally diagnosed cases with schizencephaly. Maternal characteristics, ultrasonography, prenatal-postnatal magnetic resonance imaging (MRI) findings, and postnatal outcome were noted. Of 5 cases, 2 had definitive prenatal diagnoses on ultrasound and 3 cases were diagnosed by fetal MRI. All cases had cerebral cortical migration anomalies including polymicrogyria, subependymal heterotopia, and lissencephaly, and 2 cases had additional extracranial malformations. Three cases showed regression of the cerebral clefts on follow-up postnatal MRIs. Three cases had moderate to severe psychomotor retardation, and 1 case needed repeated ventriculoperitoneal shunt operation due to hydrocephaly. Prenatal diagnosis of schizencephaly with ultrasonography is not straightforward and required further evaluation with fetal MRI. Additional cerebral anomalies worsen the prognosis of schizencephaly.

Barriers of the Human Organism and Their Achilles’ Heels

The human body is covered by barriers separating it from the external and internal surroundings. The “milieu enterieur” has to be stabilised in spite of the variable external and internal conditions of toxic, osmotic, microbial and climatic environmental circumstances. This first line of barriers is composed of skin and mucous membranes of complicated structures.

A second line of barrier system is present in our organisms. Certain organs have to be separated from the immune system and other parts of the body because of evolutionary reasons (eye-bulb and testicles) because of unique proteins “unknown” for the acquired immune system. The blood-brain barrier (BBB) is providing enhanced safety circumstances for the central nervous system. The second line of barriers is represented by the special properties of the capillary endothelial system.

The maternal-fetal barrier is the most complex. At the maternal fetal interface two individuals of two different haplotypes has to be live 9 months separated by a very complicated dynamic barrier.

The placenta is the organ, which is separating the maternal and fetal tissues. Similar to others the bidirectional transport of gasses, metabolites, cells, proteins, regulatory substances, are transported by active or passive transcellular and intercellular mechanisms.

The fetal immune system develops immunotolerance to all maternal cells and antigens transferred transplacentally. The problem is to mitigate the maternal immune system to tolerate the paternal haplotype of the fetus. In the case of normal pregnancy a complex series of physiological modifications can solve the problem without harmful consequences to the mother and fetus.

The outermost contact cells of trophoblasts express instead of HLA-class Ia and class II antigens non-variable HLA-C, HLA-E, HLA-F and HLA-G antigens. The first consequence of this is reduction of the activity of maternal natural killer cells and maternal dendritic cells;

Progesteron, micro-RNA and mediators influence the development of T effector-cells. The production of soluble HLA-G(5 and 6) and IL-10 supports the differentiation of Th-2 CD4⁺ helper cells, reducing the ability of maternal cells to kill fetal cells.

Series of receptors and costimulators are expressed by the different lines of semi-allogenic trophoblast cells to bind HLA-G and mitigate maternal immune response;

The maternal immunotolerance is further facilitated by the activation of CD4⁺CD25^brightFoxp3⁺ regulatory T (T_REG) cells.

Infections have to be prevented during pregnancy. The cells of placenta express 10 Toll-like receptors a group of pattern recognition receptors responsible for innate immunity. The interferon level is also higher in the placental tissues than in the somatic fetal or maternal cells.

The complement system is also adapted to the requirements of the pregnancy and fetal damage is inhibited by the production of “assymmetric IgG antibodies” under hormonal and placental-regulation. These modifications prevent the activation of complement, cytotoxic activity, opsonising ability, antigen clearance and precipitating activity of the molecules.

The Achilles’ heels of the different barriers are regularly found by virus infections. Lamina cribrosa of the blood-brain barrier, optical nerve of the eyes, etc. the risk factors of the maternal-fetal barrier has been summarised in Table 1.1.

Primary prevention of neural-tube defects and some other congenital abnormalities by folic acid and multivitamins: history, missed opportunity and tasks

The history of intervention trials of periconception folic acid with multivitamin and folic acid supplementation in women has shown a recent breakthrough in the primary prevention of structural birth defects, namely neural-tube defects and some other congenital abnormalities. Recently, some studies have demonstrated the efficacy of this new method in reducing congenital abnormalities with specific origin; for example, in the offspring of diabetic and epileptic mothers, and in pregnancy with high fever. The benefits and drawbacks of four possible uses of periconception folate/folic acid and multivitamin supplementation are discussed: we believe there has been a missed opportunity to implement this preventive approach in medical practice. The four methods are as follows: (i) dietary intake of folate and other vitamins, (ii) periconception folic acid/multivitamin supplementation, (iii) food fortification with folic acid, and (iv) the combination of oral contraceptives with 6S-5-methytetrahydrofolate ('folate').

Safety of oseltamivir in pregnancy: a review of preclinical and clinical data

Pregnant women with influenza are at increased risk of morbidity, particularly due to respiratory complications. A high excess mortality rate among pregnant women has been observed in previous influenza pandemics and healthcare agencies have provided recommendations on the use of oseltamivir to treat pregnant women who are infected with the pandemic (H1N1) 2009 virus. This article reviews pre-clinical and clinical data to assess the safety of oseltamivir administered during pregnancy, in the context of the effects of influenza on adverse pregnancy outcomes and fetal malformations. The effects of influenza during pregnancy, whether mediated directly by the virus or by fever or other events secondary to the underlying infection, are not yet well understood, but some data indicate an increased risk of birth defects in women infected with influenza during the first trimester. Animal and toxicology studies do not suggest that clinically effective dosages of oseltamivir have the potential to produce adverse effects on fetal development. Additionally, transplacental transfer of the drug and its active metabolite was very limited and not detectable at normal therapeutic doses in an ex vivo human placenta model. To investigate the safety of oseltamivir in pregnancy, the Roche oseltamivir safety database was searched for all exposures to oseltamivir during pregnancy in the 9 years up to 14 December 2008. In addition, a search of the literature was carried out. Of 232 maternal exposures to oseltamivir in the Roche database, pregnancy outcomes were known for 115 of these exposures. The incidence of adverse pregnancy outcomes was as follows: spontaneous abortions 6.1% (7/115), therapeutic abortions 11.3% (13/115) and pre-term deliveries 2.1% (2/94 live births), values that are not higher than background incidence rates. Fetal outcomes were known in 100 of the 232 exposures. For the nine cases of birth defect that were reported, the timing of oseltamivir exposure in relation to the sensitive period for inducing the birth defect was analysed. Two cases of ventricular septal defect, a more common birth defect, and one case of anophthalmos, an uncommon birth defect, were consistent with exposure to oseltamivir during the sensitive period for these birth defects. For other birth defects, there was either no exposure to oseltamivir during the sensitive period for the defect or insufficient information for assessment. These findings were consistent with other reports in the published literature, including a series of 79 Japanese women exposed to oseltamivir during the first trimester. Together with the other evidence reviewed herein, review of the company safety database suggests that oseltamivir is unlikely to cause adverse pregnancy or fetal outcomes, but available data are limited. Clinicians who use oseltamivir in pregnant women should consider the available safety information, the pathogenicity of the circulating influenza virus strain, the woman's general health and the guidance provided by health authorities. Roche will continue to monitor all reports of oseltamivir use during pregnancy.

Possible association between symptomatic cholelithiasis-complicated cholecystitis in pregnant women and congenital abnormalities in their offspring--a population-based case-control study

OBJECTIVE

To estimate the risk of congenital abnormalities in the offspring of pregnant women with symptomatic cholelithiasis and complicated cholecystitis.

STUDY DESIGN

Comparison of the occurrence of medically recorded symptomatic cholelithiasis and complicated cholecystitis occurred any time of pregnancy (particularly in the second and/or third gestational month) of pregnant women who had malformed foetuses/newborns (cases) and who delivered healthy babies (controls) in the population-based Hungarian Case-Control Surveillance System of Congenital Abnormalities.

RESULTS

Of 22,843 cases with CA, 62 (0.27%) had mothers with symptomatic cholelithiasis, while 119 (0.31%) mothers of 38,151 controls were recorded with symptomatic cholelithiasis. In addition, the mothers of 109 cases (0.48%) were affected by complicated cholecystitis during pregnancy compared with 145 controls (0.38%). Regarding the frequency, these two biliary diseases did not show any significant differences in the maternal variables, therefore case mothers were combined. The analysis of specific groups of congenital abnormalities showed an association between symptomatic cholelithiasis-complicated cholecystitis in the second and/or third gestation months, and neural tube defects (adjusted OR with 95% CI: 4.1, 1.3-13.4).

CONCLUSION

A higher rate of neural tube defects was found in the offspring of mothers with severe diseases of the biliary system during pregnancy. This finding needs to be confirmed by further studies and/or explanations to determine whether it is causal or a chance event.