Birth Weight Reference Percentiles by Gestational Age for Turkish Twin Neonates

In their interesting study, Yalin Imamoglu et al.¹ created up-to-date, twin-specific birth weight nomograms for both genders that could serve as a reference for the neonatologists and pediatricians in Turkey to detect high-risk neonates and fetuses who require specialized health care. Yalin Imamoglu et al.¹ addressed few study limitations. I assume that the following methodological limitation might affect the clinical relevance of the constructed nomograms. Among many determinants, parental ethnicity is an important determinant of birth weight, gestational age, and fetal growth in twin pregnancies.² Birth weight nomograms for twins have been generated for certain multi-ethnic populations.^3-4 Throughout its history, the land of Turkey has welcomed many ethnic groups and cultures. Modern Turkey was established on the land of the Ottoman Empire and took over a complex, rich multi-ethnic and multi-cultural structure.⁵ Regrettably, in the study methodology, Yalin Imamoglu et al.¹ didn’t consider the ethnic background of the studied population. Hence, this limitation might curb the employment of the created nomograms in clinical and research settings.

Funding Statement

The author declared that this study has received no financial support.

Authors’ Response

Re: Birth Weight Reference Percentiles by Gestational Age for Turkish Twin NeonatesEbru Yalın İmamoğlu1, Mutlu Hayran2, Sinan Mahir Kayıran3, Gözde Zeybek4, Sibel Sevük Özümüt1, Güner Karatekin5, Fahri Ovalı1, Tuğba Gürsoy61Department of Neonatology, Goztepe Training and Research Hospital, SB Istanbul Medeniyet University, Istanbul, Turkey2Department of Preventive Oncology, Institute of Oncology, Hacettepe University, Ankara, Turkey3Department of Pediatrics, American Hospital, Istanbul, Turkey4Department of Pediatrics, Sancaktepe Şehit Prof. Dr. İlhan Varank Education and Research Hospital, University of Health Sciences, Istanbul, Turkey5Neonatal Intensive Care Unit, Zeynep Kamil Maternity and Children Training and Research Hospital, Istanbul, Turkey6Department of Pediatrics, Koç University School of Medicine, Istanbul, Turkey

We have read with interest the letter pertaining to the ethnicity of our patients. We appreciate that ethnicity is an important demographic factor in the growth and development of infants and twins. Furthermore, the population in Turkey consists of people from many ethnic backgrounds. However, these ethnicities have merged for a very long time, and the current Turkish population has become a mixture of ethnicities. There are some people from minor ethnic groups, but we think that these people could not reach statistical significance to affect the results of our study. These ethnicities are not clear-cut as these are between Caucasian and Black people; hence, we considered that the people living in Turkey represent a rather homogenous population, distinct from Black, Chinese, Hispanic, Arab, and African people. Moreover, we did not include patients from other countries, including immigrants from Syria, Afghanistan, Uzbekistan, Turkmenistan, and other Middle Asian countries, as well as Russians and people from European Countries. The same holds true for other studies that have been conducted in Turkey on various parameters and even growth charts for singletons.^1,2 Even in the study by Premkumar et al., the subjects have been classified as Taiwanians and foreigners, without any mention of ethnicity.³ For practical purposes, we think that our nomograms may be used and would give better information than other nomograms that have been developed in other countries and in other ethnicities. Further studies with a larger series may yield better results.