Foetal thymus size in pregnancies after assisted reproductive technologies

Comparative sonographic measurement of the fetal thymus size in singleton and twin pregnancies

OBJECTIVES

The aim of this study was to compare the size of the thymus gland of healthy fetuses in twin and singleton pregnancies using the thymic-thoracic ratio (TTR). As a second objective, the TTR difference between monochorionic and dichorionic twin thymus size was examined. Finally, a possible correlation between thymus size and gestational age (GA) at birth in twin pregnancies was investigated.

METHODS

The TTR was measured retrospectively using the plane of three-vessel view in prenatal ultrasound examinations. Images of 140 healthy twin fetuses (33 monochorionic and 107 dichorionic) between 19+0 and 33+2 weeks of gestation were utilized and compared to 248 healthy singleton fetuses.

RESULTS

A significant difference in thymus size could be observed between healthy fetuses from singleton and twin pregnancies (p<0.001). Thymus size in monochorionic and dichorionic fetuses did not differ. If only comparing fetuses after 37+0 weeks of pregnancy, the difference in the TTR was no longer significant. In addition, an association between prematurity and larger thymus was established. However, the effect size of this association was small.

CONCLUSIONS

The results indicate that factors related to preterm birth, rather than the number of fetuses, are likely to influence the TTR. Utilizing fetal thymus size in ultrasound screening may hold potential for predicting adverse events like preterm birth in both singleton and twin pregnancies, but only in addition to other variables.

Ultrasonographic Evaluation of the Fetal Thymic-Thoracic Ratio in Pregnant Women With Asthma

PURPOSE

To investigate the thymic-thoracic ratio (TTR) in pregnant women with asthma to determine whether fetal thymus size is affected in this condition.

METHODS

A total of 139 patients, 69 patients diagnosed with asthma and 70 controls were prospectively included in the study at a single tertiary center. Eighteen of the patients diagnosed with asthma experienced at least one asthma attack, while 51 patients did not have any asthma attacks during pregnancy. TTR was calculated from the anterior-posterior dimensions of the thymus and intrathoracic mediastinal measurements.

RESULTS

TTR was found to be statistically significantly lower in patients with asthma compared to the controls (p < 0.001). The rate of neonatal intensive care unit admission was higher and the TTR value was lower among the cases presenting with an asthma attack during pregnancy compared to patients without asthma attack and controls (p = 0.043 and p = 0.001, respectively). A statistical difference was found between patients with and without asthma attacks regarding the use of medication for asthma (p < 0.05).

CONCLUSION

The fetal thymus has been found to be affected in patients with asthma. The TTR is lower in patients who have asthma attacks during pregnancy and in patients taking medication for treatment, which may be related to chronic inflammatory process as well as to the use of exogenous steroids.

Assessment of fetal thymus size in pregnancies of underweight women

OBJECTIVES

The aim of this study was to compare the fetal thymus size measured in the second and third trimester of pregnancy in underweight women and women with normal weight. We hypothesized that the low maternal weight would affect the fetal thymus size, as maternal health and nutrition during pregnancy affect fetal development, including that of the fetal immune system.

METHODS

The fetal thymus size was retrospectively assessed by determining the thymic-thoracic ratio in 77 pregnancies of underweight women (study group) and 85 pregnancies of women with normal weight (control group) between the 19th and 34th week of pregnancy. The anteroposterior thymic diameter and the intrathoracic mediastinal diameter were measured in the three-vessel view acquired from routine echocardiograms. The thymic-thoracic ratio was calculated by dividing the anteroposterior thymic diameter with the intrathoracic mediastinal diameter. Additionally, we compared the descriptive data between the two groups, such as gestational age at screening and at birth, birth weight, umbilical artery pH and APGAR-score after 5 min.

RESULTS

The mean fetal thymic-thoracic ratio in underweight women was not significantly different to that in normal weight pregnancies (0.374 vs. 0.363). However, the average gestational age at birth, birth weight and APGAR-score at birth were lower in the group of underweight women.

CONCLUSIONS

There is no evidence that low maternal weight influences fetal thymus size during pregnancy. The differences we observed concerning fetal weight at birth, gestational age at delivery, APGAR-Score and birth weight percentile confirm the results of previous studies.

Gross movement counting of fetuses conceived with assisted reproductive technology using a fetal movement acceleration measurement recorder

To investigate whether assisted reproductive technology (ART) affects gross fetal movement. A prospective cohort study. 65 women who conceived with ART (ART group) and 211 women (control group) without ART recorded fetal movement with the fetal movement acceleration measurement recorder at night weekly after 28 weeks. The number ratio of 10 s epochs with fetal movement to all epochs was calculated as the fetal movement parameter. When no fetal movement was observed for more than 5 min, it was defined as a no fetal movement period, and the average number per hour, the average duration, and the longest duration of the no fetal movement periods were calculated as the no fetal movement parameters. Gestational weeks were classified into 28-33 and 34-39 weeks, and the fetal movement parameter and the no fetal movement parameters were compared using the Student's t-test. The fetal movement parameters at 28-33 weeks were 17.43% (ART) and 16.58% (control) (p = 0.219), and those at 34-39 weeks were 11.72% (ART) and 11.96% (control) (p = 0.590). In the same way, for the no fetal movement parameters, the average numbers were 1.58 and 1.63 per hour (p = 0.357), and 2.36 and 2.30 per hour (p = 0.503). The average durations were 8.30 and 8.46 min (p = 0.712), and 9.20 and 9.51 min (p = 0.188). The longest durations were 16.26 and 17.02 min (p = 0.295), and 22.34 and 22.87 min (p = 0.534). ART does not affect gross fetal movement count.

Evaluation of fetal thymus size in maternal autoimmune diseases: systemic lupus erythematosus, Sjögren's syndrome and antiphospholipid antibody syndrome

PURPOSE

To investigate the effect of inflammation on the fetal thymus-thoracic ratio (TTR) in pregnant women with systemic lupus erythematosus (SLE), Sjögren's syndrome (SS) and antiphospholipid antibody syndrome (APS).

METHOD

This prospective case-control study included 45 pregnant women with SLE, SS, and APS and 90 gestational age-matched healthy pregnant women between 24 and 37 gestational weeks. The ratio of the anteroposterior fetal thymus length to the transverse mediastinal length was calculated as the TTR in the study groups.

RESULTS

Fetal TTR was significantly lower in the case group (p < 0.001). Fetal TTR in the APS group was significantly lower than SS group (p = 006). The patients using hydroxychloroquine (HCQ) had significantly higher fetal TTR compared to patients not using HCQ (p = 0.004). A moderate negative correlation was found between the disease duration and fetal TTR (r =  - 0.552, p < 0.001). In predicting admission to the neonatal intensive unit care (NICU), a value of 0.31 was found for the fetal TTR with a sensitivity of 83.3% and a specificity of 69% CONCLUSION: Maternal inflammation in pregnancies with autoimmune diseases may affect the intrauterine milieu of the fetus and cause a lower fetal TTR. Additionally, the lower level of fetal TTR may be more effective and beneficial for the clinician if combined with other risk factors in predicting NICU admission.

Decreased fetal thymus size in pregnancies after assisted reproductive technologies

OBJECTIVE

To compare the size of the fetal thymus, using both fetal thymic-thoracic ratio and fetal thymus transverse diameter values in Assisted reproductive technologies (ART) or naturally conceived pregnancies.

METHODS

In this retrospective study, fetal thymic-thoracic ratio and fetal thymus transverse diameter were evaluated in 204 pregnant women. Patients were examined in two groups. The study included 58 Intracytoplasmic sperm injection (ICSI) patients (study group) and 146 healthy pregnant women (control group).

RESULTS

Fetal thymic-thoracic ratio in ART pregnancies were found to be statistically significantly lower than that of the control group (p = .001). Also, the fetal thymus transverse diameter value was found to be statistically significantly lower in ART pregnancies compared to that of the control group (p = .001).

CONCLUSIONS

The size of the fetal thymus, manifested with a decrease in both fetal thymic-thoracic ratio and thymus transverse diameter values, decreased in ART pregnancies.

Assessment of fetal thymus size in pregnant women with rheumatic diseases: A case-control study

PURPOSE

To investigate the fetal thymic-thoracic ratio (TT-ratio) in pregnancies diagnosed with rheumatoid arthritis (RA) and ankylosing spondylitis (AS).

METHODS

Thirty-two pregnant women with rheumatic disease and 96 low-risk pregnant women between 20 and 37 weeks were included in the study. Three control patients were randomly selected for each study patient. TT-ratio was calculated by measuring the anterior-posterior diameter of the thymus and the intrathoracic mediastinal diameter. Data were compared between the study group, including RA and AS, and the control group.

RESULTS

Thirty-two pregnant women with arthritis, 19 diagnosed with RA and 13 with AS, were evaluated. The mean value of the study group TT-ratio was 0.33; control group, 0.36; a statistically significant difference was found (p < 0.001). Perinatal outcomes were not different when compared with control patients. There was a negative correlation between disease duration, maternal C-reactive protein, erythrocyte sedimentation rate, and TT-ratio.

CONCLUSION

This is the first study to prospectively evaluate the fetal TT-ratio in patients with RA and AS. Systemic inflammation appears to affect fetal thymus size. Appropriate management of maternal rheumatic diseases is essential for developing the thymus, a vital immune system component.

Fetal Thymus Size at 19-22 Weeks of Gestation: A Possible Marker for the Prediction of Low Birth Weight?

INTRODUCTION

The purpose was to compare thymus size measured during second trimester screening of fetuses who were subsequently small for gestational age at birth (weight below 10th percentile, SGA group) with fetuses with normal birth weight (control group). We hypothesized that measuring the fetal thymic-thoracic ratio (TT-ratio) might help predict low birth weight.

METHODS

Using three-vessel view echocardiograms from our archives, we measured the anteroposterior thymus size and the intrathoracic mediastinal diameter to derive TT-ratios in the SGA (n = 105) and control groups (n = 533) between 19+0 and 21+6 weeks of gestation. We analyzed the association between TT-ratio and SGA adjusted to the week of gestation using logistic regression. Finally, we determined the possible TT-ratio cut-off point for discrimination between SGA and control groups by means of receiver operating characteristics (ROC) curve analysis.

RESULTS

The TT-ratio was significantly higher in the SGA group than in the control group (p < 0.001). An increase of the TT-ratio by 0.1 was associated with a 3.1-fold increase in the odds of diagnosing SGA. We determined that a possible discrimination cut-off point between SGA and healthy controls was achieved using a TT-ratio of 0.390 (area under the ROC curve 0.695).

CONCLUSION

An increased TT-ratio may represent an additional prenatal screening parameter that improves the prediction of birth weight below the 10th percentile. Prospective studies are now needed to evaluate the use of fetal thymus size as predictive parameter for adverse fetal outcome.

Finding the best method for screening for gestational diabetes mellitus: fetal thymic-thoracic ratio or fetal thymus transverse diameter

OBJECTIVE

The aim of this study was to compare the efficiency of fetal thymic-thoracic ratio and fetal thymus transverse diameter measurements in gestational diabetes mellitus.

METHODS

Fetal thymic-thoracic ratio and fetal thymus transverse diameter were assessed in 360 pregnant women. Patients were examined in two groups: 180 gestational diabetes mellitus (study group) and 180 healthy pregnant women (control group).

RESULTS

There were no statistically significant differences between the cases with gestational diabetes mellitus and the control group in terms of fetal thymus transverse diameter; however, the fetal thymic-thoracic ratio was found to be significantly lower in cases with gestational diabetes mellitus compared to that in the control group (p<0.001).

CONCLUSION

The fetal thymic-thoracic ratio is superior to the fetal thymus transverse diameter in evaluating the fetal thymus size.

Correlation of first-trimester thymus size with chromosomal anomalies

OBJECTIVES

The aim of this study was to investigate the correlation between fetal thymus size measured during first-trimester screening and chromosomal anomalies.

METHODS

This study is a retrospective evaluation, in which the anterior-posterior diameter of the thymus in a midsagittal plane was measured in first-trimester ultrasound between 11⁺⁰ and 13⁺⁶ weeks of gestation in 168 fetuses with chromosomal anomalies (study group) and 593 healthy fetuses (control group). The included cases were subdivided into six groups: (1) trisomy 21, (2) trisomy 18, (3) trisomy 13, (4) Turner syndrome, (5) triploidy and (6) normal controls. Thymus size measurements were adjusted to the week of gestation, which was determined by ultrasound using crown-rump-length (CRL), by calculating a ratio between CRL and thymus size (CRL-thymus-ratio). Each study group was compared with the control group separately.

RESULTS

Thymus size in fetuses affected by trisomy 18 or trisomy 13 was noticeably smaller compared to the control group (1.4 mm [1.3, 1.5] and 1.3 mm [1.2, 1.4] vs. 1.8 mm [1.6, 2.1]; all p<0.001; respectively). The thymus size of fetuses with trisomy 21 and Turner syndrome did not differ from healthy fetuses. Between the CRL-thymus-ratios of the separate study groups no statistically noticeable differences could be found.

CONCLUSIONS

Fetal thymus size appeared to be smaller in pregnancies affected by trisomy 18 and trisomy 13. The predictive value of fetal thymus size in first-trimester screening should be evaluated prospectively.