Background: Pregnancy is a physiological process in which the fetus develops in the body.  Where underweight pregnancies are those with a Body Mass Index of <18.5kg/m2.  In pregnant women there will be many changes in the systems in the body.  Apart from that, pregnant women need sufficient nutrition to consume.  Nutritional status in the body can be obtained and obtained from food intake, and apart from food intake, pregnant women also need additional nutrition in the form of macronutrients and micronutrients such as omega 3 fatty acids, namely DHA. This research aims to find out whether there is an influence  between HbA1c and DHA administration to pregnant women. 

Method: This research uses an experimental type of research with a cohort research design, using one group pretest-posttest. By providing treatment to pregnant women at community health centers who meet the inclusion and exclusion criteria. 

Results: Underweight pregnant women who were researched at the Made Surabaya Community Health Center with an age range of 21 to 36 years and a Body Mass Index ranging from 17.3 kg/m2 to 18.80 Kg/m2 were given supplementation in the form of DHA in this study. (Docosahexanoid acid) for one full month to be consumed by pregnant women. 

Conclusion: this study was that there was a decrease in HbA1c levels in underweight pregnant women