Spitting up or mild vomiting in a 1.5-month-old baby is quite common and often due to immature lower esophageal sphincter function. Since you're already keeping the baby upright after feeds and vomiting still occurs, using a slightly inclined pillow or wedge under supervision can be helpful.
Next Steps
You may use a firm, inclined baby pillow (15–30° angle) under the baby's upper body, making sure- Baby is always placed on the back (not side or stomach).
Baby is supervised while on the incline.
The pillow is wide and stable to prevent rolling.
Health Tips
Avoid soft pillows or overly steep inclines, as they pose a risk of suffocation.
Feed smaller amounts more frequently and burp well.
If vomiting is forceful, green, or the baby has poor weight gain or irritability, please consult a pediatrician for evaluation of reflux or other concerns.