ABSTRAK Anemia merupakan masalah yang sering dijumpai pada kehamilan, terutama di negara berkembang. Dampak anemia pada kehamilan adalah infeksi maternal, IUGR, BBLR, prematuritas, dan mortalitas. Pada bayi IUGR, ukuran kepala kecil saat kelahiran merupakan faktor penting dalam memprediksi perkembangan neurologi yang buruk. Pertumbuhan otak yang terganggu pada masa janin dan bayi dapat mengarah pada fungsi kognitif yang lebih buruk di masa anak-anak. Penelitian ini merupakan suatu studi deskriptif-analitik dengan pendekatan cross sectional. Penelitian dilakukan di RSUP H. Adam Malik Medan selama bulan Juli 2010 sampai dengan Agustus 2010. Sampel penelitian adalah 45 orang ibu hamil dan 45 orang bayi baru lahir. Sampel dipilih sesuai dengan kriteria inklusi dan kriteria eksklusi melalui teknik consecutive sampling. Data penelitian didapatkan melalui rekam medis sampel. Data penelitian diolah dengan menggunakan program SPSS 17.0 dan dianalisis dengan uji Chi Square. Tujuan penelitian ini adalah untuk mengetahui karakteristik kadar hemoglobin pada ibu hamil, karakteristik lingkar kepala pada bayi baru lahir, serta hubungan antara kadar hemoglobin ibu hamil dengan lingkar kepala bayi baru lahir di RSUP H. Adam Malik Medan. Pada penelitian ini, terdapat 19 orang (42,2%) ibu hamil anemia dan 2 orang (4,4%) bayi baru lahir mikrosefal. Ibu hamil anemia ditemukan paling banyak pada kelompok usia 31-35 tahun (47,7%) dan ibu multipara (57,9%). Bayi baru lahir mikrosefal hanya ditemukan pada ibu dengan kelompok usia 31-35 tahun (100,0%) dan ibu multipara (100,0%). Bayi baru lahir mikrosefal memiliki distribusi yang merata berdasarkan jenis kelamin dan kadar hemoglobin ibu. Hasil uji Fisher’s Exact mendapatkan p value lebih besar daripada α (p value = 1,0 > α = 0,05 (95% CI)). Dari hasil penelitian tersebut, dapat disimpulkan bahwa tidak terdapat hubungan antara kadar hemoglobin ibu hamil dengan lingkar kepala bayi baru lahir. Asuhan prenatal dan pemantauan nutrisi perlu dilakukan secara rutin selama masa kehamilan. Kata kunci : ibu hamil, kadar hemoglobin, bayi baru lahir, lingkar kepala Universitas Sumatera Utara ABSTRACT Anemia is a common problem in pregnancy, especially in developing countries. The affects of anemia during pregnancy are maternal infection, IUGR, low birth weight, prematurity, and mortality. In infant with IUGR, small head size at birth is an important predictor of subsequent adverse neurodevelopment. Impaired brain growth in utero and in infancy may lead to poorer cognitive function in childhood. This research was a descriptive-analytic cross sectional study. It had been held at RSUP H. Adam Malik Medan on July 2010 until August 2010. Samples of the research were 45 pregnant women and 45 newborn babies. Samples were chosen based on inclusion criteria and exclusion criteria with consecutive sampling technic. Research data were collected from samples’ medical record. Research data were processed with SPSS 17.0 and analyzed with Chi Square tests. The aims of the research were to know the character of hemoglobin concentration in pregnant women, the character of head circumference in newborn babies, also the relation between hemoglobin concentration of pregnant woman and head circumference of newborn baby in RSUP H. Adam Malik Medan. In this research, there were 19 (42,2%) anemic pregnant women and 2 (4,4%) microcephaly newborn babies. Anemic pregnant women were mostly found in 31-35 years aged group (47,7%) and multiparity (57,9%). Microcephaly newborn babies were only found in women with 31-35 years aged group (100,0%) and multiparity (100,0%). Microcephaly newborn babies had an equal distribution based on sex and women’s hemoglobin concentration. Fisher’s Exact test found that p value was more than α (p value = 1,0 > α = 0,05 (95% CI)). From the result of the research, we concluded that there was no relation between hemoglobin concentration of pregnant woman and head circumference of newborn baby. Prenatal care and nutritional monitoring need to be performed regularly during pregnancy. Keywords : pregnant woman, haemoglobin concentration, newborn baby, head circumference Universitas Sumatera Utara