This is a sign your baby needs to be weighed, to ensure she has not lost too much weight. All may be well, but you cannot know this without an accurate weight.
Whenever this question comes up on mumsnet there is always a number of people who say it is fine for a baby to go without pooing for ages.
THIS ONLY APPLIES TO OLDER BABIES! Sorry for shouting :)
In the first week - like this baby - not pooing is a POTENTIALLY risky sign. Midwives should NOT be telling mothers that the only important thing is wet nappies.
When a baby is feeding well, and the milk has come in, meconium clears from the gut and the baby starts producing yellow poo from day 4-5.
When a baby is not feeding well, this doesn't happen. It sometimes happens that things are ok, or just slow to get going, and there is no problem.....but the only way to tell is to weigh the baby to get the fuller picture. A baby who's feeding well and is healthy has stopped losing weight by day 5-6 though may well not be at birth weight.
Research shows it is a good idea to weigh by day 4, then you can get a clear picture - you can step in and fix the feeding before it causes problems, and you can also compare weights if you weigh again day 5 or 6.
But in the UK, babies may not be weighed after birth until day 6 - this is not a problem with healthy babies, but too often, this weight on day 6 gives everyone a shock and there's a panic to get more milk into the baby.
There's usually no need to panic - more frequent, more effective feeding should be the response, and works fine in all but the most serious cases.
OP, can you ask someone to come and weigh your baby today? Or go to the clinic yourself today? And in the meantime, feed on both breasts very often?
The NCT sheet is correct about what to expect in the first week.
Please can we stop reassuring mothers of new babies that lack of poo is ok?
It isn't.