bb janin ku 2.8 di usia 34 week

Bun, mau tanya gmn caranya biar bb janin saat lahir nanti tetap normal ga overweight. Khawatir banget pas usg bb janin 2.8kg di usia 34 week. Mau diet takut bahaya, takut kurang darah jg. Yg aman gmn yah bun?