Birth weight discordance in spontaneous versus induced twins: impact on perinatal outcome

Prevalence and Factors Associated With Intertwin Birth Weight Discordance Among Same-Sex Twins in Lombardy, Northern Italy

This population-based cohort study investigated the prevalence, potential risk factors, and consequences of birth weight discordance (BWD) among same-sex twins. We retrieved data from the automated system of healthcare utilization databases of Lombardy Region, Northern Italy (2007-2021). BWD was defined as 30% or more disparity in birth weights between the larger and the smaller twin. Multivariate logistic regression was used to analyze the risk factors of BWD in deliveries with same-sex twins. In addition, the distribution of several neonatal outcomes was assessed overall and according to BWD level (i.e., ≤20%, 21-29, and ≥30%). Finally, a stratified analysis by BWD was performed to assess the relationship between assisted reproductive technologies (ART) and neonatal outcomes. We identified 11,096 same-sex twin deliveries; 556 (5.0%) pairs of twins were affected by BWD. Multivariate logistic regression analysis showed that maternal age ≥35 years (OR 1.26, 95% CI [1.05,5.51]), low level of education (OR 1.34, 95% CI [1.05, 1.70]), and ART (OR 1.16, 95% CI [0.94, 1.44], almost significant due to the low power) were independent risk factors for BWD in same-sex twins. Conversely, parity (OR 0.73, 95% CI [0.60, 0.89]) was inversely related. All the adverse outcomes observed were more common among BWD pairs than non-BWD ones. Instead, a protective effect of ART was observed for most neonatal outcomes considered among BWD twins. Our results suggest that conception after ART increases the risk of developing a high disparity between the weights of the two twins. However, the presence of BWD may complicate twin pregnancies, compromising neonatal outcomes, regardless of the modality of conception.

Protein C global assay evaluation in naturally conceived vs. assisted reproduction-achieved twin pregnancies: a prospective longitudinal study

PURPOSE

Protein C global assay tests the global function of the protein C pathway, the most clinically significant anticoagulant pathway in humans. The objective of this study is to assess the difference in protein C global assay levels, throughout twin gestation, in naturally conceiving and ART-treated women.

METHODS

This is a prospective cohort longitudinal study of pregnant women with twin gestation. Protein C Global evaluation was performed on frozen blood samples. Ninety-eight women with twin pregnancy, thirty-eight naturally conceived and sixty following ART, were evaluated on four occasions: during the first, second, and third trimesters, and 6 weeks or later after delivery (baseline).

RESULTS

Protein C global assay levels were lower throughout pregnancy as compared to basal levels in both the naturally conceived and ART-conceived groups. However, protein C global assay levels were similar between the ART-conceived and naturally conceived twin pregnancies in all three trimesters. Perinatal complications were associated with decreased protein C global assay levels during the third trimester, although no difference was encountered between naturally conceived and ART-complicated twin pregnancies.

CONCLUSION

While protein C global assay levels drop during twin pregnancy, there is no difference between ART-conceived and naturally conceived gestations. Decreased levels of protein C global assay during the third trimester were similarly associated with perinatal complications in both groups. Our results imply that twin pregnancy of itself is a more dominant factor for perinatal complications as compared to other factors, such as subfertility or the exposure to ART per se.

Associations between estimated foetal weight discordance and clinical characteristics within dichorionic twins: The NICHD Fetal Growth Studies

BACKGROUND

Birthweight discordance is well studied, with less known about longitudinal inter-twin differences in foetal growth.

OBJECTIVE

To examine inter-twin per cent differences in EFW (EFW_% ), head (HC_% ) and abdominal circumference (AC_% ), and femur length (FL_% ) across gestation in dichorionic twin gestations and explore associated characteristics.

METHODS

Foetal biometrics were assessed by ultrasound and EFW calculated at ≤6 study visits among women with dichorionic twin pregnancies enrolled in the NICHD Fetal Growth Studies cohort (US, 2012-2013). Inter-twin per cent difference was defined: ([Size_{larger twin}  - Size_{smaller twin} ]/Size_{larger twin}  × 100). Linear mixed models evaluated per cent differences in foetal biometrics at 15 weeks and their change per week overall and by maternal/neonatal characteristics in unadjusted and adjusted models.

RESULTS

In 140 pregnancies, inter-twin per cent differences increased across gestation for EFW (0.18%/week, 95% confidence interval [CI] 0.10, 0.27), HC (0.03%/week, 95% CI 0.00, 0.06), and AC (0.03%/week, 95%CI -0.01, 0.08) but decreased for FL (-0.03%/week, 95% CI -0.09, 0.02). After adjustment, change in EFW_% difference across gestation differed by pre-pregnancy body mass index (BMI [kg/m² ]; underweight [<18.5]; normal weight [18.5-24.9]; overweight [25.0-29.9]; obese [≥30.0]; P_interaction  = .022); and conception method (in vitro fertilisation [IVF], intrauterine insemination, ovulation induction medication, donor egg/embryo, none; P_interaction  = .060). While EFW_% difference increased with normal pre-pregnancy BMI (0.24%/week, 95% CI 0.12, 0.37), little change was noted with pre-pregnancy obesity (0.01%/week, 95% CI -0.15, 0.17). EFW_% difference increased in conceptions without fertility treatments (0.23%/week, 95% CI 0.11, 0.34) but not IVF conceptions (-0.00%/week, 95% CI -0.16, 0.16). Similar patterns of differences across gestation were noted for HC_% by conception method (P_interaction  = .026) and AC_% by pre-pregnancy BMI (P_interaction  = .071); changes in HC_% differed by parity (nulliparous, multiparous; P_interaction  = .004).

CONCLUSIONS

EFW_% difference increased across gestation in dichorionic twins, but remained stable with pre-pregnancy obesity or IVF conception, patterns mirrored for HC and AC. Research is needed to understand pathologic versus physiologic differential twin growth trajectories.

Children Born Small for Gestational Age: Differential Diagnosis, Molecular Genetic Evaluation, and Implications

Children born small for gestational age (SGA), defined as a birth weight and/or length below -2 SD score (SDS), comprise a heterogeneous group. The causes of SGA are multifactorial and include maternal lifestyle and obstetric factors, placental dysfunction, and numerous fetal (epi)genetic abnormalities. Short-term consequences of SGA include increased risks of hypothermia, polycythemia, and hypoglycemia. Although most SGA infants show catch-up growth by 2 years of age, ∼10% remain short. Short children born SGA are amenable to GH treatment, which increases their adult height by on average 1.25 SD. Add-on treatment with a gonadotropin-releasing hormone agonist may be considered in early pubertal children with an expected adult height below -2.5 SDS. A small birth size increases the risk of later neurodevelopmental problems and cardiometabolic diseases. GH treatment does not pose an additional risk.

Birth weight discordance and adverse perinatal outcomes

OBJECTIVE

Our purpose was to examine the association between discordant growth and perinatal mortality and morbidity among twins with careful adjustment for maternal confounding factors.

STUDY DESIGN

Two cohorts with and without chorionicity data were compared using generalized estimating modeling.

RESULTS

Our population-based dataset consisted of 12,656 individual twins from whom 4% (452/12,656) had≥30% growth discordance. A subgroup of this population with chorionicity information had an incidence of 7.3%≥30% growth discordance. In growth-discordant twins, perinatal mortality and morbidity were higher than concordant pairs (P<0.01). Low Apgar score and perinatal mortality were more frequent in growth-discordant twins compared with growth-concordant ones (all P<0.01).

CONCLUSION

Birth weight discordance (BWD) places twins at increased risk of perinatal mortality. Growth discordance was also an independent risk factor for lower Apgar score of 5 min less than 5.

Fertility treatment and dichorionic discordant twins - are they related?

OBJECTIVE

This prospective cohort study evaluated the relationship between fertility treatments and the prevalence and outcomes of dichorionic discordant twins. This issue has gained importance due to twin gestations resulting from fertility treatments.

STUDY DESIGN

Mothers of dichorionic twin pregnancies achieved in a single fertility clinic by assisted reproduction techniques, who had completed the first trimester of the pregnancy, were prospectively enrolled. Pregnancies with major fetal anomalies were excluded. Data regarding concordant and discordant twins based on the fertility treatments given to achieve the pregnancies were analyzed to determine the prevalence of discordance and pregnancy outcomes.

RESULTS

A total of 571 dichorionic twin pregnancies were available for evaluation. Fertility treatments modalities, sperm quality and implantation of cultured and thawed embryos did not influence the rate and severity of discordant twins. Increased hospitalization rates were found among discordant (n=108) compared to concordant (n=463) twins (47.2% vs. 31.3%, P<0.0001) and higher rates of betamethasone treatment (65.7% vs. 28.9%, P<0.0001). Secondary analysis of discordant pregnancies with a growth restricted twin, revealed the same results. We found no association between various fertility treatments and twin discordance.

CONCLUSIONS

Our data suggest that fertility treatments do not play a major role in the pervasiveness and outcome of discordant twin pregnancies.

Intrauterine growth pattern and birthweight discordance in twin pregnancies: a retrospective study

BACKGROUND

Twins, compared to singletons, have an increased risk of perinatal mortality and morbidity, due mainly to a higher prevalence of preterm birth and low birthweight. Intrauterine growth restriction (IUGR) is also common and can affect one or both fetuses. In some cases, however, one twin is much smaller than the other (growth discordance). Usually, high birthweight discordance is associated with increased perinatal morbidity. The aim of this study is to describe the epidemiological features of a population of twins at birth, with particular reference to the interpretation and clinical effects of birthweight discordance.

METHODS

We evaluated retrospectively the clinical features of 70 infants born from twin pregnancies and assessed birthweight discordance in 31 pregnancies where both twins were followed at our institution. Discordance was treated both as a continuous and a categorical variable, using a cutoff of 18%. Possible relationships between birthweight discordance and other variables, such as maternal age, gestational age, birthweight percentile, number of SGA newborns in the pair, Hematocrit (Ht) discordance and neonatal anemia, prevalence of malformations, neonatal morbidity and death, were analyzed.

RESULTS

In our cohort birthweight percentile decreased slightly with increasing gestational age. Birthweight discordance, on the contrary, increased slightly with the increase of gestational age.A high discordance is associated to the presence of one SGA twin, with the other AGA or LGA. In our population, all 6 pregnancies in which discordance exceeded 18% belonged to this category (one SGA twin).Ht discordance at birth is associated to the presence of neonatal anemia in a twin, but it is not significantly related to weight discordance.Finally, in our case history, weight discordance is not associated in any way with the prevalence of malformations, morbidity and mortality.

CONCLUSIONS

Birthweight discordance is an important indicator of complications that act asymmetrically on the two fetuses, affecting intrauterine growth in one of them, and usually determining the birth of a SGA infant.Our case history shows a significant statistical association between pair discordance and IUGR in one of the twins, but we could not demonstrate any relationship between discordance and the prevalence of malformations, morbidity and mortality.

Growth discordance

Poor growth is a common problem in twin pregnancies, and management poses some unique challenges as the wellbeing of both twins have to be taken into account at all times. The decision to deliver the twins to prevent an intrauterine demise of the growth-restricted twin will, therefore, depends on the chances of intact postnatal survival of both twins. In monochorionic twins, management is complicated further by the fact that the wellbeing of one twin critically depends on that of the other twin because of the shared circulation. In the event of demise of the growth-restricted twin, the larger twin may also die or sustain brain damage because of an acute exsanguination into the feto-placental unit of its demised co-twin. In the pre-viable period, invasive fetal therapy may, therefore, be indicated to protect the appropriately growing twin.

Discordant twins: diagnosis, evaluation and management

Approximately 16% of twin gestations have discordance of at least 20%. We identified 14 risk factors for divergent growth that can be categorized as maternal, fetal, or placental. Determination of chorionicity and serial ultrasound evaluation with a high index of suspicion for divergent growth is required for the diagnosis and stratification of risk. The highest reported likelihood ratio for detection of discordance was 5.9 during the first trimester examination and 6.0 for the second trimester. Although our ability to identify discordant twins is limited, once suspected and at viable gestational age, these pregnancies should have antepartum testing. Discordant growth alone is not an indication for preterm birth. Although there are multiple publications on the increased morbidity and mortality rates with discordant growth, there is a paucity of reports on how to manage them optimally and deliver them in a timely manner.

Differences in short-term neonatal outcomes between discordant twins

PURPOSE

To evaluate short-term outcomes associated with discordant twin pairs admitted to the NICU.

DESIGN

A retrospective descriptive study comparing discordant twin pairs.

SUBJECTS

Three hundred eighty-four discordant twin pairs were included. Mean gestational age of the twin pairs was 32.6 weeks (range, 24-39).

METHODS

The ParadigmHealth database was queried for all twin admissions from January 2001 to June 2004 admitted to 453 NICUs across the United States. Discordance was calculated for each twin set as defined as greater than 20% difference in birth weight. Exclusion criteria were death of a twin, congenital anomalies, or extracorporeal life support.

MAIN OUTCOME MEASURES

Demographics, respiratory needs, feeding characteristics, complications, and discharge needs.

RESULTS

A total of 384 discordant twin pairs met inclusion criteria. The larger twins required more ventilation/continuous positive airway pressure (55% vs 44%, P < .01) and/or oxygen therapy (50% vs 41%, P = .02) compared with smaller twins. Smaller twins reached full oral (PO) feeds an average of 0.6 weeks later than larger twins (P < .0001) but had more weight gain per day. Smaller twins transitioned to an open crib at lower weights but at slightly greater age. No differences were noted with necrotizing enterocolitis or apnea. Smaller twins had increased nosocomial infections. Mean length of stay was shorter (P = .0036) in the larger twin group. Only 33% of the twin pairs were discharged on the same day.

CONCLUSIONS

Larger twins had more acute respiratory issues but achieved certain milestones more rapidly with fewer complications, thus leading to earlier discharge compared with their smaller twin counterparts.

Twin pregnancy outcome among cases of spontaneous conception, intrauterine insemination, and in vitro fertilization/intracytoplasmic sperm injection

In a retrospective university hospital-based study of spontaneously conceived (SC), intrauterine insemination (IUI), and in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) groups, this study finds maternal complications or the neonatal outcomes of twins to be similar between the groups.