Hi.. I'm a mother of twins.. They were born exactly at 35 weeks. The girl was 1.9kg & boy was 1.6 kg. Now they are 2 weeks short of their 4 months bday. The girl now is 5.6kg while the boy is only 4.2 kg. I wonder if introducing solids at 4 mths is ok or is it considered too early as they are preemies. Would the boy benefit from taking solids as in he will gain more weight? Any input or advice?