Last updated:
March 31, 2026
The most reliable method of estimating gestation age is using the last normal menstrual period (LNMP).
Other methods include sonography, or the Ballard method, post-partum.
Small for gestational age (SGA) is not synonymous with low birth weight (LBW). SGA implies a problem with growth, whereas LBW implies a baby who is small at the time of birth, even though they may not be SGA.
LBW is defined simply as weight alone, while SGA is defined as the weight relative to gestational age.
The baby’s size relative to gestational age is plotted on a growth chart to show the percentile
Reference Intervals
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Biochemistry
| ACTH | P: <80 ng/L |
| ALT | P: 5–35 U/L |
| Albumin | P: 35–50 g/L |
| Aldosterone | P: 100–500 pmol/L |
| Alk. phosphatase | P: 30–130 U/L |
| α-Amylase | P: 0–180 IU/dL |
| α-Fetoprotein | S: <10 kU/L |
| Angiotensin II | P: 5–35 pmol/L |
| ADH | P: 0.9–4.6 pmol/L |
| AST | P: 5–35 U/L |
| Bicarbonate | P: 24–30 mmol/L |
| Bilirubin | P: 3–17 μmol/L |
| BNP | P: <50 ng/L |
| CRP | P: <10 mg/L |
| Calcitonin | P: <0.1 mcg/L |
| Calcium (ionized) | P: 1.0–1.25 mmol/L |
| Calcium (total) | P: 2.12–2.60 mmol/L |
| Chloride | P: 95–105 mmol/L |
| Cholesterol | P: <5.0 mmol/L |
| VLDL | P: 0.128–0.645 mmol/L |
| LDL | P: <2.0 mmol/L |
| HDL | P: 0.9–1.93 mmol/L |
| Cortisol AM | P: 450–700 nmol/L |
| Cortisol Midnight | P: 80–280 nmol/L |
| CK ♂ | P: 25–195 U/L |
| CK ♀ | P: 25–170 U/L |
| Creatinine | P: 70–100 μmol/L |
| Ferritin | P: 12–200 mcg/L |
| Folate | S: 2.1 mcg/L |
| FSH | P: 2–8 U/L ♂; >25 menopause |
| GGT ♂ | P: 11–51 U/L |
| GGT ♀ | P: 7–33 U/L |
| Glucose (fasting) | P: 3.5–5.5 mmol/L |
| Growth hormone | P: <20 mu/L |
| HbA1C (DCCT) | B: 4–6% |
| HbA1C (IFCC) | B: 20–42 mmol/mol |
| Iron ♂ | S: 14–31 μmol/L |
| Iron ♀ | S: 11–30 μmol/L |
| Lactate (venous) | P: 0.6–2.4 mmol/L |
| Lactate (arterial) | P: 0.6–1.8 mmol/L |
| LDH | P: 70–250 U/L |
| LH | P: 3–16 U/L |
| Magnesium | P: 0.75–1.05 mmol/L |
| Osmolality | P: 278–305 mosmol/kg |
| PTH | P: 0.8–8.5 pmol/L |
| Potassium | P: 3.5–5.3 mmol/L |
| Prolactin ♂ | P: <450 U/L |
| Prolactin ♀ | P: <600 U/L |
| PSA | P: 0–4 mcg/mL |
| Protein (total) | P: 60–80 g/L |
| Red cell folate | B: 0.36–1.44 μmol/L |
| Renin (erect) | P: 2.8–4.5 pmol/mL/h |
| Renin (recumbent) | P: 1.1–2.7 pmol/mL/h |
| Sodium | P: 135–145 mmol/L |
| TBG | P: 7–17 mg/L |
| TSH | P: 0.5–4.2 mU/L |
| T4 | P: 70–140 nmol/L |
| Free T4 | P: 9–22 pmol/L |
| TIBC | S: 54–75 μmol/L |
| Triglycerides | P: 0.50–2.3 mmol/L |
| T3 | P: 1.2–3.0 nmol/L |
| Troponin T | P: <0.1 mcg/L |
| Urate ♂ | P: 210–480 μmol/L |
| Urate ♀ | P: 150–390 μmol/L |
| Urea | P: 2.5–6.7 mmol/L |
| Vitamin B12 | S: 0.13–0.68 nmol/L |
| Vitamin D | S: 50 nmol/L |
Arterial Blood Gases
| pH | 7.35–7.45 |
| PaCO₂ | 4.7–6.0 kPa |
| PaO₂ | >10.6 kPa |
| Base excess | ±2 mmol/L |
Urine
| Cortisol (free) | <280 nmol/24h |
| Hydroxyindole acetic acid | 16–73 μmol/24h |
| Hydroxymethylmandelic acid | 16–48 μmol/24h |
| Metanephrines | 0.03–0.69 μmol/mmol cr. |
| Osmolality | 350–1000 mosmol/kg |
| 17-Oxogenic steroids ♂ | 28–30 μmol/24h |
| 17-Oxogenic steroids ♀ | 21–66 μmol/24h |
| 17-Oxosteroids ♂ | 17–76 μmol/24h |
| 17-Oxosteroids ♀ | 14–59 μmol/24h |
| Phosphate (inorganic) | 15–50 mmol/24h |
| Potassium | 14–120 mmol/24h |
| Protein | <150 mg/24h |
| Protein/creatinine ratio | <3 mg/mmol |
| Sodium | 100–250 mmol/24h |
Haematology
| WCC | 4.0–11.0 ×10⁹/L |
| RBC ♂ | 4.5–6.5 ×10¹²/L |
| RBC ♀ | 3.9–5.6 ×10¹²/L |
| Hb ♂ | 130–180 g/L |
| Hb ♀ | 115–160 g/L |
| PCV ♂ | 0.4–0.54 L/L |
| PCV ♀ | 0.37–0.47 L/L |
| MCV | 76–96 fL |
| MCH | 27–32 pg |
| MCHC | 300–360 g/L |
| RDW | 11.6–14.6% |
| Neutrophils | 2.0–7.5 ×10⁹/L (40–75%) |
| Lymphocytes | 1.0–4.5 ×10⁹/L (20–45%) |
| Eosinophils | 0.04–0.44 ×10⁹/L (1–6%) |
| Basophils | 0–0.10 ×10⁹/L (0–1%) |
| Monocytes | 0.2–0.8 ×10⁹/L (2–10%) |
| Platelets | 150–400 ×10⁹/L |
| Reticulocytes | 0.8–2.0% / 25–100 ×10⁹/L |
| Prothrombin time | 10–14 s |
| APTT | 35–45 s |
Paediatric
| Pulse Rate (bpm) | |
|---|---|
| Neonate | 140–160 |
| Infant <1yr | 120–140 |
| 1–5 years | 110–130 |
| 5–12 years | 80–120 |
| >12 years | 70–100 |
| Respiratory Rate (tachypnoea) | |
| 0–2 months | ≥60/min |
| 2–12 months | ≥50/min |
| 1–5 years | ≥40/min |
| >5 years | ≥30/min |
| Blood Pressure (mmHg) | |
| Term | 65/45 |
| 1 year | 75/50 |
| 4 years | 85/60 |
| 8 years | 95/65 |
| 10 years | 100/70 |
| Weight Formulas | |
| 3–12 months | (a + 9)/2 kg |
| 1–6 years | 2a + 8 kg |
| >6 years | (7a − 5)/2 kg |
| Haemoglobin (g/dL) | |
| Term newborn | 13–20 |
| 1 month | 11–18 |
| 2 months | 10–15 |
| 1–2 years | 10–13 |
| >2 years | 11–14 |
| MUAC (6 months–5 years) | |
| Obese | >17.5 cm |
| Normal | 13.5–17.4 cm |
| At risk | 12.5–13.4 cm |
| Moderate malnutrition | 11.5–12.4 cm |
| Severe malnutrition | <11.5 cm |
| Developmental Milestones | |
| Social smile | 1.5 months |
| Head control | 4 months |
| Sits unsupported | 7 months |
| Crawls | 10 months |
| Stands unsupported | 10–12 months |
| Walks | 12–13 months |
| Talks | 18 months |
| CSF WBC (/mm³) | |
| Term newborn | 0–25 |
| >2 weeks | 0–5 |
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