Resuscitating the neonate

A baby should breathe within a minute of birth, and usually does so. If he does not, he needs resuscitating, which may make all the difference between normality and brain damage. ''Flat' babies, who don't breathe, are often a surprise, but you should be able to predict and prepare for most of them as described below. Most follow difficult deliveries, which are more likely to damage his brain by anoxia during and after delivery, than by trauma during it.

The aim of resuscitation is to make sure that his lungs expand, he is well oxygenated, his circulation and temperature are normal, and he is breathing normally. Mask ventilation and intubation will not help him if he does not need them; so follow the indications below.

Ideally, all your midwives should be able to intubate a baby. They can learn how to do it on a fresh stillbirth. But if normal deliveries are done by a continuously changing succession of midwives in training, you will not be able to train all of them to intubate the occasional baby who needs it. For these babies immediate bag and mask, or mouth to mouth ventilation, will be much better than intubation delayed by the time it takes to call you.

Traditionally, the Apgar score has been used to decide which babies to resuscitate. The instructions given below simplify this, and use only the heart rate and the respirations, on the grounds that if these are unfavourable, the other parts of the score will be unfavourable too. See also Primary Anaesthesia Chapter 13.

LARYNGOSCOPE, neonatal, straight-bladed, Seward, with two blades sizes 0 (80 mm) and 1 (110 mm), also ten spare batteries and five spare bulbs, two laryngoscopes only. You will need a spare laryngoscope[md]at least one of them must be working [f10]always!.

TUBES, tracheal, neonatal, transparent, plastic or rubber, non[nd]disposable (or disposable but reusable), either Cole pattern with neck and T-piece, or straight pattern with uniform diameter and stylet (optional), sizes 2.5 mm (10 Ch), 3 mm (12 Ch), and 3.5 mm (14 Ch), ten only of each size. Pack these locally in sets.

ADAPTOR, tracheal, neonatal, various sizes, five only. This fits the tracheal tubes to the Ambu bag.

SUCTION CATHETERS, 4, 6, 8, and 10 Ch, ten only of each size. These fit down the tracheal tubes.

AIRWAYS, neonatal, sizes 00 and 000, five only of each size. One contributor considers these outmoded.

MASK, neonatal, soft and clear, sizes 00, 0, and 1, Ambu (AMB) Laerdal, Bennett, or Samson, two only of each size.

BAG, self-inflating, neonatal or infant size 250 or 500 ml, Cardiff, Laerdal, or Ambu (AMB), with reservoir or extension tube, and expiratory pressure release valve, one only. The pressure release valve will prevent you inflating him at [mt]40 cm of water. The valves must be present and working.

SUCTION DEVICE, electric, with overflow bottle and gauge, maximum vacuum 100[nd]120 mm Hg (0.16[nd]0.26 Bar), as ''de Vilbiss 721 Vacu Aide' (deV), one only. Don't use a standard anaesthetic sucker[md]it sucks much too powerfully. Alternatively, use a mucus extractor, see below.

FOOTPUMP, ''minipump' Ambu (AMB), one only. You will need this if you don't have electricity, or it fails.

MUCUS EXTRACTOR tube and fluid trap, 10 Ch (CHI), five only. If necessary, you can make these from old drip sets. The danger with a mucus extractor is that you may get secretions in your mouth, which is not acceptable where HIV is a risk. Unfortunately, there is presently no mouth-operated sucker which avoids this.

STETHOSCOPE, with small head, one only.


RESUSCITATING THE NEWBORN ''AT RISK' MOTHERS AND BABIES. Causes arising during labour (1) Fetal distress. (2) Meconium staining of the liquor. (3) Caesarean section. (4) Vacuum or forceps delivery (except a simple ''lift out'). (5) Abnormal presentation, commonly breech delivery. (6) Prolapsed cord. (7) APH, especially placenta praevia. (8) Prolonged labour. Maternal conditions. (1) Diabetes. (2) Fever. (3) Other maternal illnesses. (4) Extremes of maternal age ([lt]16 or [mt]35 years). (5) Heavy sedation. The excessive administration of pethidine ([mt]100 mg 4-hourly during labour). Contrary to popular belief, pethidine in reasonable doses (100 mg 6- to 8-hourly) causes only minimal neonatal depression. (6) Babies whose mothers have severe gestational hypertension (pre-eclampsia) which has required heavy sedation, particularly with diazepam, or phenobarbitone (not advised). Fetal conditions (1) Multiple pregnancy. (2) Pregnancy of abnormal length ([lt]37 weeks, or [mt]42 weeks). (3) Prematurity. (4) IUGR (19.13). (5) Isoimmunization. (6) Abnormal babies.

CAUTION ! When you start any operative delivery, make sure that the midwife who is helping you is completely ready to resuscitate the baby.

WARMTH. The first principle in caring for a baby is to keep him warm and keep him fed. Hypothermia is one of the most easily avoidable causes of neonatal death in low birthweight babies, even in ''warm' countries, so keep him warm and dry during all the procedures which follow! He can easily lose 3[de]C in 15 minutes, with dangerous consequences, which include hypoglycaemia, respiratory distress, and acidosis. If you can keep the whole room at 30[de]C (very uncomfortable for adults), you will not need an additional heater. If you cannot maintain this temperature, keep the room as warm as you can (24[nd]26[de]C is a good compromise) and provide a radiant heater (a lamp is almost useless) over the resuscitation platform, with sides to prevent drafts. Use dry towels and keep them warm near a radiator or in a warm cupboard. Survey the temperatures of babies arriving in your neonatal ward. You may be surprised by how cold some of them are! Later, the best place to keep him warm is between his mother's breasts, which will also assist breast-feeding and bonding.

OXYGEN (with spare cylinders) is desirable, but not essential. It must reach him at a pressure of not more than 30 cm of water (20 cm is is the usual working pressure), so there must be a blow-off valve which prevents it exceeding this pressure. Provide one by using a T[nd]tube and a water manometer, as in U, Fig. 19-13, if necessary made from old drip sets. If you don't have oxygen, you will have to ventilate him by mouth (see below).

THE RESUSCITATION PLATFORM can be horizontal, or slightly sloping head-down. It can be the top of a suitably prepared trolley, or a broad shelf attached to the wall at a convenient height.

OTHER EQUIPMENT AND DRUGS should be kept immediately available on a trolley. Besides the special equipment listed above, you will need: Warm towels. Feeding tubes 6 and 8 Ch. Needles 0.5, 0.6 and 0.8 mm. A stopclock indicating seconds and minutes. Scalp vein sets and paediatric infusion sets. 1 cm adhesive tape to secure the tube. ''BMstix' or ''Dextrostix' to measure the blood glucose; note the expiry date, and economize by cutting strips in half lengthwise. Blood sugar bottles.

10 ml ampoules of 8.4% (1 mmol/ml) sodium bicarbonate, 10% calcium gluconate, 5% and 10% dextrose in water, and 0.9% sodium chloride. 10% oral dextrose. Naloxone hydrochloride (expensive but seldom needed): neonatal 20[gm]g/ml for intravenous use, or adult 400 [gm]g/ml. Dilute 1 ml of the adult naloxone with 20 ml of saline for neonatal use. Don't have both because you can easily mistake them. 1 mg ampoules of vitamin K[,1]. 3 ml ampoules of 1:10,000 adrenalin. If you only have 1 ml ampoules of 1:1000 adrenalin, dilute one of these with 10 ml of saline.

CAUTION ! (1) Ask another person to check all drugs before you give them. (2) Don't use nikethamide, caffeine, or aminophylline, or other central stimulants. (3) Older drugs, such as nalorphine and levallorphan, may cause respiratory depression, if you don't give them at exactly the right dose for a particular situation. (4) Keep all drugs in their original boxes and not together as ''mixed ampoules'.

Check the equipment regularly, keep a log book, and sign it. Clean and disinfect the equipment after use (2.5, 28a.2).

INTRAVENOUS INJECTIONS. Catheterizing the umbilical vein is more likely to cause infection; a scalp vein drip is safer. If a baby needs intravenous injections, give them into the drip or directly into the umbilical vein with a syringe and needle; be sure you are in the vein and not in the tissues.

IMMEDIATELY AFTER BIRTH Start the clock. Hold him for a moment with his head lower than his legs, so that fluid drains from his respiratory tract. Place him on the resuscitation platform. Quickly dry him with a warm towel; dry his hair, axillae, and groins. Remove the wet towel and cover him with a dry one.

Leave his cord at least 3 cm long, with the nearest tie at least 2 cm from him, so that it can be used for intravenous injection if necessary. Don't apply alum powder to it for at least 24 hours.

If he is BREATHING NORMALLY AND CRYING VIGOROUSLY, with a good heart rate and normal colour and muscle tone, he usually needs no suction. But if there are copious secretions or blood in his mouth, gently suck out his oropharynx (see below). Briefly clear his nose, and hand him to his mother.

If he has MECONIUM-STAINED LIQUOR, you MUST clear his airway. If possible, do this as soon as his head is delivered, before he takes his first breath. When he has been delivered, hold his chest to prevent inspiration, until you have cleared his pharynx and larynx under direct vision with a laryngoscope. This is difficult, and it may be easier to intubate and suck through the tracheal tube.

If there is only a little meconium, intubate him, and aspirate it with a suction catheter through the tube.

If there is much meconium, aspirate immediately with the largest possible catheter, or quickly connect suction to a tracheal tube. If a catheter or tracheal tube blocks, remove it and quickly replace it with another. Continue until all meconium is cleared, unless there is bradycardia ([lt]60/minute); if so intubate him immediately. If his condition allows it, avoid ventilation until you have removed as much meconium as you can.

If his BREATHING IS SHALLOW AND IRREGULAR, estimate his heart rate by listening to it, by feeling his umbilical cord pulsating or his brachial pulse.

If it is [mt]100/min, and he is well perfused, with good tone, apply tactile stimulation and an airway. Gently flick the soles of his feet, or rub his back for a few seconds. Be gentle, and if there is no prompt response, stop, suck out his oropharynx and start mask ventilation.

If it is [lt]100/min, insert an airway and start mask ventilation.

If he NEVER BREATHED, or STARTED TO BREATHE AND THEN STOPPED, start bag and mask ventilation. If his heart rate is still [lt]100 after one minute of ventilation (he is usually pale and limp), apply suction briefly and intubate him immediately.

SUCKING HIM OUT If necessary (see above), first suck out his mouth, then his nose with a sterile, wide, soft rubber or plastic catheter, or use a standard ''disposable but reusable' mouth sucker with a fluid trap. Give one long, strong suck, and don't push the catheter [mt]5 cm from his mouth.

CAUTION ! Before you start to ventilate him by any method, be sure to suck him out. Sucking out his trachea is as important as ventilating him. If you don't suck him out, you may push liquor, mucus, or meconium deeply into his bronchi.

Fig. 19-13 NEONATAL RESUSCITATION. A, a transparent Laerdal self-inflating bag; note the valve. B, compress the bag with your finger tips. C, a straight-sided tube. D, a Cole tube with side arm and stylet (optional). E, lift his epiglottis. Or F, put the blade of the laryngoscope into his vallecula. G, and H, lift his tongue forwards to view his larynx. I, gently press on his trachea with your 5th finger. J, or ask an assistant to do this. K, and L, the correct position for resuscitation. M, his neck is too extended. N, it is too flexed. O, the correct size of mask. P, it overlaps his chin. Q, it is too small. R, it overlaps his eyes. S, and T, inserting an infant airway. U, a T-tube and water manometer adjusted so as not to exceed a pressure of 20 cm of water. V, mouth to mouth ventilation. Blow gently from your cheeks only, about 40 times a minute. Lift up his chin, extend his head and keep him warm.

BAG AND MASK VENTILATION Slightly extend his neck, if necessary with a small pad under his shoulders. Insert an oral airway (optional). Put a finger under his mandible to hold it forwards, without compressing the soft tissues of his neck K, and L, Fig. 19-13. Choose the largest mask which will not overlap his eyes or his chin (O).

Gently compress the bag with your finger tips (B), so as to inflate him 30[nd]60 times a minute with as high a concentration of oxygen as you can, usually at a flow of 2[nd]6 litres/minute. You can increase the oxygen concentration by fitting a reservoir or additional length of hose over the air intake (A). Watch his chest, it should rise with each breath. Don't compress the bag suddenly and forcefully. The object of each inflation with the mask is to expand his lungs and start him breathing.

If his chest does not rise with each breath: (1) Check that the mask makes an adequate seal with his face. (2) If necessary, clear his airway again by sucking out his mouth and nose. (3) Does the bag leak? (4) If necessary, insert an infant airway (S, and T). If this fails, intubate him. If you cannot intubate him, try compressing the bag harder.

If mask ventilation fails, intubate him promptly.

INTUBATION INDICATIONS. The failure of mask ventilation. Don't intubate him unless his heart rate and general condition deteriorate, and not until after you have sucked out his pharynx and larynx under direct vision. Unskilled attempts at intubation do more harm than good. Most ''floppy' babies can survive without it, provided you ventilate them in some other way.

METHOD. Neonatal intubation resembles adult intubation (A 13.1). Prepare the tracheal tube you think you will need. Cole tubes (C) do not require a stylet. If you use a stylet, curve it to the shape of the tube and don't let it protrude beyond the end.

[lt]1250 g or [lt]28 weeks 2.5 mm tube.

1250 g[nd]2 kg or 29[nd]34 weeks 2.5 or 3 mm tube.

[mt]2 kg or [mt]34 weeks 3 or 3.5 mm tube.

''Big baby' 3.5 mm tube.

Slightly extend his head on his neck (K and L). First try to ventilate him with a mask for a few breaths. Gently insert a laryngoscope with a straight blade (size 0 blade for a small preterm baby and size 1 for a larger one) with your left hand, holding his lips apart with the fingers of your right hand. Guide the blade over the surface of his tongue, pushing it to the left. Continue until you see his leaf-like epiglottis. Either lift his epiglottis gently (E), or insert the blade into his vallecula (F). Lift his tongue forwards, so that you can see his larynx (G and H). If you insert the blade too far into his oesophagus, withdraw it gradually until you can see his larynx.

Clear his vocal cords and posterior pharynx with a sucker. Gently press on his trachea with your 5th finger (I) (or ask an assistant to press it, J) until you can see his cords. Using your right hand pass the tube between his cords from the right, until the shoulder (Cole type) or mark (straight type) is just above his cords.

CAUTION ! (1) Make sure his trachea remains central. (2) Don't force the shoulder of a Cole tube through his cords. (3) If his cords are obscured by secretions, ask your assistant to hand you the suction catheter and gently clear his airway. (4) Don't overextend his neck; the ''sniffing position' (A 13-7) is ideal. (5) If he is seriously in need of ventilation, intubation is best[md]if you are sure the tube is in his trachea. If you are not sure, mask ventilation is safer.

Rest your hand gently on his face, hold the tube firmly, and gently remove the laryngoscope (and stylet if you are using one). Connect the tube to the oxygen supply, and adjust it to deliver 4 l of oxygen per minute at 20 to 30 cm of water (use a lower pressure for a very small baby).

Inflate his lungs by occluding the outlet of the tube (U), or the T-piece of a Portex tube, and watching the column of air in the manometer. Or squeeze an Ambu bag. If he has never made any inspiratory effort (primary apnoea), his lungs will be more difficult to expand, so apply more pressure (the ''opening pressure') for slightly longer with his first breath. Inflate him for 2[nd]3 seconds initially, and then for about half a second at 30[nd]60 breaths per minute. If he has taken a few breaths and then stopped (secondary apnoea), he will need less pressure to inflate his lungs. Often, you cannot distinguish primary from secondary apnoea.

Observe: (1) His chest moving; and check that the movements are equal both sides. (2) His breath sounds; and check that they are also equal both sides. (3) An increase in his heart rate. (4) An improvement in his colour.

As soon as you are ventilating him effectively, so that his heart rate is [mt]100, dry him and replace the wet towel with a dry one. Continue ventilating him until he breathes spontaneously himself. Note the time at which he first breathes.

If he does not start breathing spontaneously in a few minutes, strap the tube in place with tape and continue ventilating.

If you fail to intubate him within 20[nd]30 seconds, withdraw the tube and ventilate him with a mask (to improve his colour and increase his heart rate) before you try to intubate him again.

If his chest movement is poor after intubation, check the flow-meter. Is the oxygen on? Is the oxygen cylinder empty? Is the tube blocked (suck it out) or kinked (straighten it)? If none of these are responsible, it is probably in his oesophagus, so remove it and try again.

If secretions are copious pass a suction catheter down the tube and aspirate them.

If his breath sounds and chest movements are asymmetrical, the tube is probably in his right main bronchus. Slowly withdraw it 0.5 cm at a time, listening for his breath sounds to become equal. If they continue to be inadequate, he may have a pneumothorax, a diaphragmatic hernia, a pleural effusion, or hypoplastic lungs (not described here).

If his heart rate remains [lt]100, check that the tube is not in his right main bronchus (see above). If it is [lt]50 he needs cardiac compression (see below).

ENDING VENTILATION. When he is pink and his heart rate is [mt]150, stop ventilation and watch him carefully; if his heart slows, start ventilating him again. Let him try breathing on his own, when his heart rate is [mt]150. He may need an occasional puff before regular breathing restarts. When he is breathing regularly remove the tube.

CAUTION ! (1) Don't remove him from the labour ward with the tube in place. (2) Don't leave him on a sloping resuscitation platform: the weight of his liver pressing on his diaphragm will make breathing difficult. (3) If he has been in any way abnormal, watch him carefully for 24 hours.

If he does not start breathing or his heart rate remains [lt]50 for 30[nd]45 minutes, stop. He is unlikely to survive.

Fig. 19-14 EXTERNAL CARDIAC COMPRESSION. A, grasp the baby's chest with both hands. B, C and D, another method of compressing his chest. E, and F, while you intermittently compress his heart 120 times a minute, ask a colleague to inflate him 30[nd]60 times a minute.

EXTERNAL CARDIAC COMPRESSION INDICATIONS. If his heart beat is [lt]50/minute (bradycardia), compress his heart in the hope of strengthening or restarting it. He is usually pale. If his heart is not beating at birth, external cardiac massage is unlikely to start it.

METHOD. Grasp his chest with both hands and place your thumbs over his sternum at the level of his nipples (A, Figure 19-14). Gently compress his chest 1[nd]1.5 cm. When you relax, keep your fingers on his chest. While you intermittently compress his heart 120 times a minute (B, C, and D), ask a colleague to inflate him 60 times a minute (E and F). Time this by calling out to your assistant ''One, two, (compressions)[md]breathe'' (One contributor advises 100 compressions and 30 breaths, in which case it is about three compressions to a breath). Check his heart rate after 30[nd]60 seconds and thereafter periodically. Observe or feel his pulses or listen to his heart.

CAUTION ! (1) Don't press over his liver. (2) He needs cardiac compression and ventilation.

DRUGS [s7]FOR NEONATAL RESUSCITATION Prompt ventilation will correct his acidosis and will be safer than giving him a bolus injection of sodium bicarbonate. Difficult intravenous injections have a low priority; ventilation is critical.

If he has persistent bradycardia ([lt]50) in spite of adequate ventilation and cardiac compression, give him 2 mmol/kg of sodium bicarbonate intravenously. Either give 2 ml/kg of 8.4% sodium bicarbonate (1 mmol/ml) or 4 ml/kg of the 4.2% solution (this is a more convenient dilution to give: make it by diluting the 8.4% solution with an equal volume of 5% dextrose or water). One contributor gives sodium bicarbonate to any ''flat' baby. If you have catheterized his umbilical vein, always flush with 0.9% saline before and after giving sodium bicarbonate.

If he has persistent bradycardia or no heart beat after bicarbonate, give him 0.1 ml/kg of 1:10,000 adrenalin intravenously, or down the tracheal tube. If necessary, repeat the dose after10[nd]15 minutes.

If adrenalin fails to improve persistent severe bradycardia or make his heart beat return, give him 1[nd]2 ml (0.1[nd]0.2 g) of 10% calcium gluconate intravenously slowly. Never give this with sodium bicarbonate. Flush with saline or 5% dextrose first.

CAUTION ! Continue ventilation and cardiac compression.

If his respiration is depressed and his mother has had a narcotic (pethidine), ventilate him first if necessary, and give him one dose of naloxone. Either 200 [gm]g intramuscularly (60 [gm]g/kg). Or, 40 [gm]g intravenously (10 [gm]g/kg).

HYPOGLYCAEMIA [s7]IN NEONATES DIAGNOSIS. Hypoglycaemia is one of the more preventable causes of death in the first hours or days of a baby's life. He is at risk if: (1) He is underweight, either premature or ''small for dates' (IUGR). (2) He has been hypoxic perinatally. (3) His mother had gestational hypertension (''pre- eclampsia'), uncontrolled diabetes, or severe sepsis.

The symptoms of hypoglycaemia are ill-defined. Think of it in any baby you have resuscitated who is jittery, tremulous, apnoeic, lethargic, hypotonic, or who has an abnormal cry, or who feeds poorly or has convulsions.

MANAGEMENT. Give him 5 ml/kg of 10% dextrose intravenously. If he improves, becomes more alert and stops convulsing, continue giving him dextrose 100 ml/kg/24 hours intravenously and small volumes of expressed breast milk.

If possible, test a heel-prick sample of his blood with ''BMstix', and repeat this 6-hourly, just before feeds, for the first 24 hours or longer if necessary. If ''BMstix' reads [lt]2.5 mmol/l, he is hypoglycaemic. If possible, send a specimen for his blood sugar to be measured in the laboratory. Continue to monitor his blood sugar with ''BMstix' for 48 hours.

Alternatively, if you cannot give him a drip, you may be able to manage him orally. Pass a nasogastric tube, and aspirate his whole gastric contents. This tells you how much of his previous feed, if any, is left in his stomach, and avoids overfilling his stomach, with the risk of regurgitation. Hypoglycaemia reduces the motility of the gut, so this is a danger in ''at risk' babies. If the aspirate contains meconium or blood, lavage his stomach with 10 ml of water or saline. Then give him 10 to 15 ml of 10% dextrose by nasogastric tube, alternating with expressed breast milk 2-hourly, so that he has 100 ml/kg/day of fluid.

LATER [s7]IN THE RESUSCITATION OF A NEONATE Check that he is pink and well perfused, his heart is normal (110[nd]130), his pulses are easily palpable, he has good tone and spontaneous movement, he is warmer than 36[de]C, his breathing is regular (40[nd]60/min) and is without distress.

Give all ''at risk' babies vitamin K[,1] (phytomenadione) 0.5 mg intramuscularly. Avoid synthetic analogues, such as menadiol sodium diphosphate (''Synkavit'), because of the risk of kernicterus.

Give him to his mother. She will have been worried while you were resuscitating him. Even if he needs special care, give her a chance to hold him before you remove him.

In the ward watch his colour and his breathing, and monitor his blood glucose with test strips. Correct his blood glucose as necessary (especially if he has IUGR). An efficient way to keep him warm is in the ''kangaroo pouch' between his mother's breasts, when she is well wrapped up, and he wears a hat (he can lose much heat from his head).

DIFFICULTIES [s7]WITH NEONATAL RESUSCITATION If you DON'T HAVE A BAG AND MASK and CANNOT INTUBATE HIM, what you and especially your midwives should do depends on the prevalence of HIV in your area:

If HIV IS RARE, use MOUTH TO MOUTH VENTILATION. Bend his head gently backwards over a rolled up towel. Put your mouth over his mouth and nose. Blow in gently. Blow with small breaths, about 40 times a minute. Don't blow from your lungs. Blow from your cheeks only. You need very little air to blow up the lungs of a small baby[md]20[nd]50 ml only. If you blow too hard, you will cause a pneumothorax. His chest should move as you blow, as if he was breathing himself. Most babies start breathing with your first two breaths. So stop after two breaths and see if he breathes. After a few inflations he should start breathing and become pink. His heart should beat faster.

If HIV IS COMMON, use the form of artificial ventilation which is known in some areas (Papua New Guinea) as ''FROG BREATHING'. Gently extend his neck over a rolled up towel, as for intubation. If you have oxygen, pass this through one nostril. Pinch his nose between your finger and thumb. With your other hand pull down his jaw, and then pull it up and close his mouth. This raises his upper ribs and increases the capacity of his chest, so that air is drawn into his lungs. Repeat this rhythmically to imitate breathing. It is surprisingly effective.

If he is VERY PRETERM ([lt]26 weeks) or very small (1000 g), suck him out and do only minimal resuscitation. You will not be able to ventilate him long-term, so don't start. If you keep him warm, he may surprise you and do well. Manage him as in Primary Child Care Section 26.22.

If the OXYGEN IS NOT WORKING, very gently blow down the tube intermittently using your cheeks. Practise by blowing down the manometer to see what a pressure of 30 cm of water feels like. Don't go above this.

KEEP HIM WARM AND KEEP HIM FED Fig. 19-15 A FUNDAL HEIGHT CHART. If low-birthweight babies are common in your district, you will find many mothers falling below the 10th centile, either because their babies have IUGR or because they are genetically small (the relative importance of these factors is unknown).