Mothers whose babies are under or over the average birthweight may be offered observations for their baby for 24 hours after the birth. Reasons for a 'small' or 'large' baby may not be initially clear to the caregiver. It may be that the baby is genetically small or large, due to their parents' build and ethnicity. If this is the case the observations could be done unnecessarily.
The concerns for the caregiver are that the baby may have an underlying health concern (such as being a baby of a mother with undetected diabetes) or that the baby may become unwell due to their body composition (having comparatively little body fat).
In past years the weight of the baby was the only defining factor to determine whether observations were required. In recent years caregivers have started to use other physical factors to identify babies 'at risk' and hopefully spare healthy under or overweight babies from unnecessary observations and interventions.
The criteria used to identify babies 'at risk' and the observations recommended for them will vary from caregiver to caregiver and hospital to hospital. The following is a guide to give you an idea of what the criteria could be and the types of observations that may be performed.
Babies who are thought to be 'underweight' (for their gestation) are referred to as small for dates or small for gestational age (SGA). Some hospitals will use arbitrary measures (say less than 2,500 to 2,800 grams - 5lb 8oz to 6lb 3 oz) if the baby is 37 to 42 weeks gestation. Others will use a set scale that determines different acceptable weights for babies at 37, 38, 39 and 40 weeks gestation. (This tends to be more accurate for detecting babies 'at risk'). Babies who are premature can also be small for dates; twins are more susceptible to being small for dates.