The first worry, of course, is whether the weight estimation is accurate! Ultrasound weight estimation is notoriously inaccurate, although it's more common for it to mistakenly label an average-sized baby as large, than small. Nonetheless, results should be taken with a pinch of salt. Don't be rushed into a decision until you feel happy with it, and if in doubt, please join the Homebirth UK email group for advice and moral support - there is sure to be someone on there who has been in a similar situation.
But what if your baby does seem to be small?
In a nutshell, the concerns are:
The issue of whether the baby is 'constitutionally small', or has a problem, is discussed in detail below.
If it looks like your baby will be small then I strongly recommend making contact with one of the voluntary breastfeeding support organisations or an expert midwife who's also a qualified lactation consultant well in advance, and to read up, in case issues arise due to early delivery and/or small baby. If you are worried about your baby, preparing for breastfeeding is the best thing you can do to look after your baby's health in future. Sometimes hospitals have a policy of routinely recommending formula top-ups for babies of low birthweight, so if it's important to you to maximise your baby's health potential through exclusive breastfeeding then you'll need to read up on this beforehand.
Personally I would always prefer the help of a specialist breastfeeding counsellor or lactation consultant, if I needed breastfeeding support, as they are the real experts in breastfeeding and will normally have plenty of suggestions for mothers of small babies. You can contact contact the voluntary breastfeeding organisations or a local breastfeeding counsellor for a chat before you give birth.
The gist of it is likely to be: Feed often, and check position, and look out for lots of wet/pooey nappies... If there is concern about the baby's glucose levels then frequent breastfeeding helps, and some women prefer to express colostrum and spoon-feed it. Supplementing with formula is also an option at home of course! However, given that even a small amount of formula at an early stage can trigger allergies to cows' milk products, it's worth fighting to maintain exclusive breastfeeding.
Many mothers find it far harder to establish breastfeeding in a hospital than they do at home, so breastfeeding issues are certainly not a compelling reason to have a baby in hospital.
In hospital a small baby may be placed on a heat pad or otherwise kept warm in an incubator.
You are, I'm sure, capable of making sure your baby doesn't get cold - stay in a warm room, use a hat on baby, and enjoy lots of skin-to-skin contact. This means snuggling up with your baby under a towel or bedclothes, so that his bare tummy is against your bare tummy. It's otherwise known as 'kangaroo care' and has had a great track record when used to nurture premature and ill babies, but is equally beneficial for any baby. A wonderful bonus is that it helps to establish breastfeeding - skin to skin contact encourages hormone production for breastfeeding and relaxes mother and baby. See Kangaroo Mother Care for lots on this wonderful and natural way of caring for your baby.
I've been told that my baby is a bit small for my dates. Can I still have a homebirth?
'A bit small' needn't be a problem; what you really need to find out is if, as is most likely, your baby is just 'constitutionally small' , ie smaller than average because that's the right size for him/her, eg if you yourself are small, OR if your baby may be suffering from intra-uterine growth restriction (IUGR), which is where the baby is not fulfilling its growth potential because it has a health problem or is not receiving enough nourishment through the placenta.
Being 'constitutionally small' isn't a big deal as far as homebirth is concerned - the issues are just keeping warm and establishing breastfeeding, both of which can be done as well or better at home as in hospital.Babies who are suffering from IUGR are at genuinely increased risk of stillbirth and other complications, especially post-dates. It's part of an obstetrician's job to help tell IUGR babies from babies who are constitutionally small, and while it's not foolproof, there are characteristics which can be used to identify IUGR babies.
Some research on post-dates pregnancy suggests that the vast majority of stillbirths post 42-weeks is actually in babies suffering from IUGR (see www.gentlebirth.org/archives/datesppr.html). It's certainly arguable that many IUGR babies might be better off in hospital, and it sounds like many will benefit from being induced before term if they really aren't doing well in the womb, but what about all the babies who are small, but who aren't suffering from IUGR? Exposing them to unnecessary intervention, and delivering them before they are ready, is not being 'on the safe side' as far as those babies are concerned; it is actually increasing their risk of problems.
Looking at the NHS guidance on Small for Gestational Age (SGA) babies, it seems it's common to flag up the 10th centile and below, and some people will call all these babies "IUGR". There is a good article about this on the NHS's patient database (http://www.patient.co.uk/showdoc/40000204/)
In fact, according to that source and others, about 7 out of 10 of those babies in the bottom 10% for size/weight will be "constitutionally small", ie this is the right size for them given their genetic background - but the remaining 3 out of 10 are suffering from growth restriction. Here's some of the text:
Of the 10% of babies with IUGR by the definition, about 7% will be constitutionally small and 3% will have pathology. Babies may be genetically small without pathology as are adults. Perhaps both parents are small. There may be racial differences. Babies of Indian race tend to be a little smaller. If the fetus is in the lower centiles but continues to grow within those centiles, this is reassuring but if growth is slow and the fetus is falling into lower centiles, this is cause for concern.
There are ways of identifying the baby who is suffering from true IUGR rather than just being constitutionally small:
By and large, when the problem is placental insufficiency, the head is not as restricted in size as the abdominal girth. This represents preferential nutrition to the brain with a lack of glycogen stored in the liver...
...Criteria suggesting IUGR include an increased ratio of femoral length to abdominal circumference, an increased ratio of head circumference to abdominal circumference and oligohydramnios.
The GROW customised growth charts are recommended by the NHS Perinatal Institute to help sort out the babies who are constitutionally small, from those who are genuinely at risk. They customise expected foetal growth based on the mother's individual size, ethnic background etc, to reduce the number of babies who are flagged up as 'small for dates' when actually they're perfect for their own family.
Here is some info from the GROW website:
GROW (Gestation Related Optimal Weight) is the software used to generate a customised antenatal growth chart. The chart is based on the calculation of an individualised weight standard for the duration of the pregnancy, adjusted for the physiological variables of maternal height, weight in early pregnancy, parity and ethnic group.
After the maternal and pregnancy details (including expected date of delivery) are entered into the software, the chart can be printed out and attached to the maternity record. The Perinatal Institute has developed hand held Pregnancy Notes (www.preg.info) with an adhesive strip for the charts and explanation of their use for fetal growth assessment.
The charts can be used for plotting fundal height and estimated fetal weight, and assessed against the individually predicted or 'customised' standard.
Here's some more References on GROW charts from the NHS Perinatal Institute about those charts - http://www.preg.info/evidence/page12/page12.htm - might be useful if you want to investigate it further, or if your midwife/doc is not familiar with the customised charts.
Another useful resource for anyone worrying about a small baby is the Royal College of Obstetricians and Gynaecologists' guidelines on the Small-for-Gestational-Age (SGA) baby, Guideline no 31, November 2002, http://www.rcog.org.uk/resources/Public/pdf/Small_Gest_Age_Fetus_No31.pdf
They say that screening tests need to be interpreted carefully as most make no allowance for other factors known to affect foetal size, such as mother's ethnicity and height, parity and foetal gender. (p2). They also say that if SGA is defined as the lowest 10% of birthweight, about 50 - 70% of these babies are constitutionally small and the rest will be suffering from Fetal Growth Restriction (FGR) - another term for IUGR. It explains that SGA babies are at increased risk of stillbirth and hypoxia and other complications, but that the reason for the increased risks is the high proportion of small babies who are actually suffering from growth restriction.
The RCOG recommend use of the GROW customised foetal growth charts because it is better at detecting small babies than the standard charts, and reduces unnecessary hospital visits for further investigations. These customised charts are apparently better for fundal height, growth scans and birthweight (p3/4). Furthermore, looking at whether the baby is growing over a period of at least two weeks is more accurate than looking at a snapshot at one point in time. The interval between scans should be at least two weeks.
They also say that :
"A systematic Cochrane review has shown that routine ultrasound after 24 weeks in low-risk pregnancy does not improve perinatal outcome". (p4)
Something else interesting: where it really does look like the baby may have a problem, umbilical artery doppler scans have been shown to significantly improve outcomes while reducing unnecessary induction and other interventions. It's not recommended as a routine screening tool, only to be used selectively where there is concern about a small baby .(p5/6). Now that does sound like a good use of the technology.
The RCOG guidelines finish with something a bit less detailed, and not as sensible-sounding to me, but I'm biased! I don't want to cherry-pick and only draw attention to the bits I agree with, though - having spent most of the paper saying, basically, most SGA babies are perfectly normal and here are ways to identify the ones who may need extra help, they then say all SGA babies should have continuous monitoring in labour. Now I suppose if you've used a customised growth chart then many babies would not be labelled as SGA in the first place, so this wouldn't apply.
Rebecca N was not expecting a small baby, but Beatrice weighed only 2.56 Kg (5lb 6oz) on arrival at term.7
Judith's third baby, Leah, weighed on 5lb 5oz at birth.
Helen M had trouble arranging a homebirth when a small baby was suspected. She made an informed decision to continue with her plans, and had a small, but healthy, baby boy at home. Great support from her NHS Supervisor of Midwives when an obstetrician was unsupportive.
Nikki Ford's baby weighed 5lb 7oz.
Suzanne's baby weighed 5lb 8oz
Claire Constable's baby was 5lb 12oz.
Laura transferred to hospital because of predicted low birthweight and low amniotic fluid - her daughter was 5lb 1 oz.
Hayley was told that her baby was small-for-dates and had low amniotic fluid, and was advised to have her labour induced at 38 weeks. She declined and her baby was born spontaneously, safe and well, weighing 7lb 8oz.
Two predicted low birthweight babies, one born in hospital and one at home, and a comparison of the care they received - on the UK Midwifery site.
GROW charts - customised fetal growth charts which can be adjusted for mother's size, ethnicity etc, as recommended by the NHS Perinatal Institute and the Royal College of Obstetricians and Gynaecologists.
NHS patient database article on small babies
References on GROW charts from the NHS Perinatal Institute
Royal College of Obstetricians and Gynaecologists' guidelines on the
Small-for-Gestational-Age (SGA) baby, Guideline no 31, November 2002
 5th Annual CESDI (Confidential Enquiry into Stillbirths and Deaths in Infancy) - HMSO
Available free online at the Confidential Enquiry into Maternal and Child Health website (www.cemach.org.uk)
Home Birth Reference Page