Insecure attachment and internalizing behavior problems in growth discordant identical twins

Two Babies, Two Bonds: Challenges in Attachment Relationships in Twins

The attachment relationship constitutes the first emotionally significant affective bond, usually between the infant and the mother, serving as a model for subsequent relationships. It is considered a vital component of social and emotional development in the early years and an important early indicator of infant mental health. In twins, the attachment process may exhibit unique characteristics, influenced by the dual parenting dynamic and the individual needs of each baby. With this article, we intend to explore the challenges of infant-caregiver relationships and the attachment process in twins through a brief, non-systematic literature review regarding a clinical case of a 21-month-old female born from a twin pregnancy complicated by selective fetal growth restriction (sFGR), prematurity, and very low birth weight. The patient was initially suspected of displaying an insecure ambivalent/resistant attachment style, differing from her twin sister. Studies have shown a high concordance in attachment style between twin pairs, although a higher prevalence of insecure ambivalent/resistant attachment style compared to the general population. This may reflect challenges commonly presented in twin pregnancies and the perinatal period, such as sFGR, prematurity, and feeding difficulties, which increase parental stress that may impair early attachment between parents and infants. Attachment is not a fixed bond. Early identification and intervention in infant-caregiver relationship difficulties within this vulnerable group can help mitigate the challenges of dual parenting, fostering secure bonds and promoting healthy infant development.

Reduced lung function during childhood in identical twins with discordant fetal growth: a cohort study

Background

Fetal growth restriction (FGR) can negatively affect lung development, leading to increased respiratory morbidity and reduced lung function later in life. Studies regarding the impact of FGR on lung function in singletons are influenced by genetic, obstetric, and maternal factors. To overcome these confounding factors, we aim to investigate lung function in identical twins with selective FGR (sFGR).

Methods

Lung function assessments were performed in identical twins with sFGR born in our centre between March 1, 2002, and December 31, 2017, aged between 5 and 17 years. sFGR was defined as birthweight discordance ≥20%. Outcome measures consisted of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and transfer factor for carbon monoxide (DLCO) and were compared between the smaller and larger twin.

Findings

Thirty-nine twin pairs performed spirometry of sufficient quality. Median gestational age at birth was 34.3 (interquartile range (IQR) 32.1-36.0) weeks with median birthweights of 1500 (IQR 1160-1880) grams and 2178 (IQR 1675-2720) grams for the smaller and larger twin, respectively. Smaller twins had significantly lower z-scores for FEV1 (-0.94 versus -0.41, p = 0.0015), FVC (-0.56 versus -0.06, p < 0.0001) and DLCO (-0.50 versus 0.00, p < 0.0001) compared to larger co-twins.

Interpretation

Although being genetically identical, sFGR in identical twins is associated with a reduction in static and dynamic lung volume and a reduction in lung diffusion, even when taking the reduced lung volume into account. This indicates that adverse growth conditions in utero negatively affect lung development and function, potentially contributing to an increase in respiratory morbidities later in life.

Funding

The Dutch Heart Foundation and The Bontius Foundation.