Razi Journal of Medical Sciences

fa اهمیت ید در بارداری و شیردهی، یک مرور روایتی Importance of Iodine during Pregnancy and Lactation, a Narrative Review مامایی Midwifery مروري review article <div style="text-align: justify;">زمینه و هدف: ید یک ماده حیاتی برای تولید هورمون‌های تیروئید و تکامل سیستم عصبی جنین و نوزاد است. این مرور نقلی ما بر نقش و اهمیت ید در دوران بارداری و شیردهی متمرکز شده و به تبین مسائل مختلف مربوط به آن می‌پردازد. روش کار: در این بررسی مروری، پایگاه‌های PubMed،Web of Science  و Scopus و نیز پایگاه‌های فارسی SID، Irandoc و Magiran، با کلمات کلیدی مناسب برای مقالات مرتبط جستجو شده و از 97 مقاله جهت این مرور نقلی استفاده گردید. یافته‌ها: کمبود ید در دوران بارداری می‌تواند باعث اختلالات جدی در عملکرد تیروئید مادر و جنین شده و منجر به عواقب نامطلوبی در بارداری گردد. زنان باردار و شیرده نسبت به سایر بزرگسالان نیاز به ید بیشتری دارند. به طوری‌که مصرف 250-220 میکروگرم در روز در بارداری و290-250 میکروگرم در روز در دوران شیردهی توصیه می‌شود. مکمل ید در صورتی که قبل از لقاح یا در سه ماهه اول و اوایل سه ماهه دوم بارداری شروع شود و در تمام دوران بارداری ادامه یابد، موثرترین راه پیشگیری از آسیب عصبی جنین است. با این حال، اگرچه مکمل ید در دوران بارداری بی‌خطر است، اما ممکن است در زنان باردار با کمبود ید خفیف که در کشورهای دارای کفایت ید زندگی می‌کنند، توجیه پذیر نباشد. نتیجه‌گیری: با توجه به ضرورت وجود ید کافی برای تکامل سیستم عصبی جنین و نوزاد و افزایش نیاز به ید در زنان باردار و شیرده نسبت به سایر بزرگسالان، مصرف مکمل ید یا غذاهای غنی از ید در این دوران توصیه می‌شود.</div> <div style="text-align: justify;">Background & Aims: Iodine is essential for the production of thyroid hormones, which regulate many bodily functions, including metabolism and growth.  Thyroid hormones are closely related to the growth, development of the nervous system, and the metabolism of substances throughout the body, thus managing various aspects of the body's metabolism. Fetal development strongly depends on thyroid and iodine metabolism, especially during critical periods of brain development (from early pregnancy to early birth), nervous system development depends on thyroid hormones and can be compromised if their function is impaired. This narrative review focuses on the role and importance of iodine during pregnancy and lactation and explains various related issues. Methods: In this narrative review, PubMed, Web of Science, and Scopus databases, as well as SID, Irandoc, and Magiran Persian databases, were searched with appropriate keywords for related articles, and 97 articles were used for this comparative review. Results: Thyroid hormone production in pregnant women increases by 50% in early pregnancy. On the other hand, the increase in the mother's blood volume during pregnancy may be associated with a decrease in the concentration of nutrients and, as a result, a decrease in their concentration in the urine. During pregnancy, maternal iodine is transferred to the fetus through the placenta and is the only source of iodine for the fetus during pregnancy, so the iodine status of pregnant women directly affects the growth and development of the fetus. Insufficient iodine intake during pregnancy can lead to a range of adverse reproductive outcomes, including increased risk of perinatal and infant mortality, and intellectual impairment in children. The most severe consequence of iodine deficiency is cretinism, a condition characterized by severe physical and mental developmental delays. Iodine deficiency during pregnancy can cause serious disorders in maternal and fetal thyroid function and lead to adverse consequences in pregnancy. Studies have shown that overt hypothyroidism due to severe iodine deficiency during pregnancy is associated with adverse outcomes including spontaneous abortion, gestational hypertension, preeclampsia, and gestational diabetes. Mother's thyroid hormone plays an important role in fetal brain development. The brain is especially sensitive to iodine deficiency during its formation in the early embryonic period and after birth. During pregnancy and early lactation, the iodine needed by children is completely taken from the mother. Insufficient iodine as well as excess may cause hypothyroidism. Indeed, iodine deficiency during pregnancy is the most important preventable cause of neurodevelopmental disorders worldwide and is an important global public health issue. Pregnant and lactating women need more iodine than other adults. In general, pregnant women need a 50% increase in iodine to produce enough thyroid hormone to meet the needs of the fetus, as well as to meet the needs of increased production and placental transfer of thyroid hormone, which is necessary for optimal fetal growth. In areas where iodine is sufficient, the mother's thyroid gland increases its iodine absorption to maintain sufficient reserves inside the thyroid. However, in moderate to severe iodine deficiency, such adaptive mechanisms may fail to maintain adequate iodine stores (4). Accordingly, the daily requirement of iodine during pregnancy increases to 250 micrograms compared to 150 micrograms for non-pregnant women. Infants are more sensitive than other age groups to abnormal changes in iodine concentration because they have the highest iodine requirement per kilogram of body weight. The development of the brain and central nervous system takes place from the second trimester of pregnancy to the age of 3 years. Breastfed infants are solely dependent on the adequate supply of iodine in breast milk for the synthesis of thyroid hormones, and the concentration of iodine in breast milk depends on the mother's dietary intake. Therefore, low maternal iodine intake inevitably predisposes lactating women and their infants to iodine deficiency. Based on this, it is clear that during this period, the mother's iodine intake should be optimal to provide enough iodine for the developing fetus. Most people get relatively small amounts of iodine in their diet, so an additional source is needed to provide them with enough iodine for their daily needs and to maintain normal thyroid hormone concentrations. Salt, enriched bread and water are the main sources of iodine. WHO recommends fortification of all dietary salt with iodine as an effective and safe strategy for the control and prevention of iodine deficiency disorders (IDD) for those living in iodine-deficient and iodine-sufficient areas. Adults need 150 micrograms of iodine per day, which varies from 90 to 290 micrograms per day based on the age and physiological status of the person. Pregnant and lactating women need more iodine than other adults. 220 to 250 micrograms per day during pregnancy and 250 to 290 micrograms per day during lactation are recommended. Accordingly, iodine supplementation during pregnancy and lactation is widely and justifiably recommended to prevent the potentially damaging and irreversible consequences of iodine deficiency on child development. Current WHO recommendations indicate that although iodine supplementation during pregnancy is safe, it may not be justified in pregnant women with mild iodine deficiency living in iodine-sufficient countries The timing of iodine supplementation seems to be very important in relation to pregnancy. All the evidence shows that iodine supplementation is most effective (probably the only effective agent) in preventing fetal neurologic damage if it is started before conception or in the first and early second trimester of pregnancy and continues throughout pregnancy. Given the timing of thyroid hormone action on the developing fetal brain, it is reasonable to start iodine supplementation for women prone to iodine deficiency before conception, if possible, to ensure adequate thyroid iodine stores. WHO, UNICEF, and ICCIDD/IGN recommend a daily dose of 250 mcg potassium iodide for lactating women. Alternatively, in countries where iodine deficiency is evident, and has not been corrected by a public iodized salt program, these authorities recommend an annual depot dose of 400 mg of iodized oil orally at 6-monthly intervals for the exclusive breastfeeding mother Conclusion: In summary, adequate iodine intake during pregnancy and lactation is vital for the health and development of the child. Considering the necessity of sufficient iodine for the development of the nervous system of the fetus and newborn and the increased need for iodine in pregnant and lactating women compared to other adults, it is recommended to take iodine supplements or iodine-rich foods during pregnancy and lactating.</div> ید, کمبود ید, بارداری, شیردهی Iodine, Iodine Deficiency, Pregnancy, Breastfeeding 1 15 http://rjms.iums.ac.ir/browse.php?a_code=A-10-5275-2&slc_lang=fa&sid=1 Fahimeh Ramezani Tehrani فهیمه رمضانی تهرانی 3900319475328460089277 3900319475328460089277 No Professor, Reproductive Endocrinology Research Center, Endocrine Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran استاد، مرکز تحقیقات اندوکرینولوژی تولید مثل، پژوهشکده غدد درون ریز، دانشگاه علوم پزشکی شهید بهشتی، تهران، ایران Sima Nazarpour سیما نظرپور snazarpour@gmail.com 3900319475328460089278 3900319475328460089278 Yes Associate Professor, Medicine Faculty, Varamin-Pishva Branch, Islamic Azad University, Varamin, Iran, & Posdoc, Reproductive Endocrinology Research Center, Endocrine Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran دانشیار، گروه مامایی، دانشکده علوم پزشکی، واحد ورامین -پیشوا، دانشگاه آزاد اسلامی، ورامین، ایران، و محقق پسادکترای مرکز تحقیقات اندوکرینولوژی تولید مثل، پژوهشکده غدد درون ریز، دانشگاه علوم پزشکی شهید بهشتی، تهران، ایران