Infanticide and Signs of Live Birth — Hydrostatic Test, Breslau Second Life Test and Legal Provisions

Infanticide is the killing of a newborn infant. In medicolegal practice the main question is whether the child was born alive, because only a living child can be the victim of homicide. A forensic autopsy on a newborn therefore sets out to distinguish live birth from stillbirth, assess fetal viability and identify traumatic or other non-natural causes of death. Suspected infanticide is especially relevant in cases of concealed pregnancy and abandonment of the newborn.

A recent forensic series defines live birth as the complete expulsion or extraction of a fetus from its mother, irrespective of gestational age, which after separation shows any evidence of life — such as breathing, heartbeat, pulsation of the umbilical cord or definite voluntary muscle movement. A fetus that shows none of these signs after birth is a stillbirth.

The Bharatiya Nyaya Sanhita (BNS), 2023 has no section called 'infanticide'. When a living newborn is killed the offence is murder (section 101 defines it; section 103 punishes it with death or imprisonment for life, and fine) or culpable homicide. The BNS does, however, contain specific provisions that matter in cases involving newborns, listed below. These replaced the corresponding Indian Penal Code sections; for the old IPC numbers see the IPC and BNS sections page.

Evidence of live birth comes from three sources: the history and circumstances (any witness who saw the baby breathe or cry), the external and internal autopsy findings, and special tests. The respiratory system gives the main proof, because a baby that has breathed has been born alive.

Examination of the placenta and umbilical cord also gives information on fetal hypoxia, intrauterine infection and vascular compromise, and may explain a death that has nothing to do with any act of the mother. Where the body is decomposed, live birth often cannot be established at all: in one forensic series, advanced decomposition prevented assessment of both live-birth status and the cause of death in two infants.

The hydrostatic test — also called the lung float test or docimasia — is an autopsy procedure used in suspected infanticide to decide whether the lungs have been aerated by respiration. The principle is simple: lungs that have breathed contain air and float in water, while unexpanded lungs of a stillborn child are airless and sink. The lungs are removed together with the cervicothoracic organs, tested in water, and cut sections can also be tested; floating of the cut pieces supports aeration.

How reliable is it? In a prospective autopsy study of 208 newborn lungs, the test gave the expected result in 204 cases (about 98%). There were four false-negative results — lungs sank although life had been reported — and no false positives. The authors concluded the test is reliable but that a negative result cannot prove that a newborn never breathed. In a more recent forensic series, the test was used as an adjunct, with the authors stressing that it should never be interpreted in isolation because false positives and false negatives occur with decomposition, artificial ventilation, severe prematurity or lung disease.

Breslau's second life test examines the stomach and intestines. After birth a breathing baby swallows air, so in a live-born child the stomach and bowel contain air and float in water, whereas in a stillborn child they are empty and sink. Forensic authors describe the test as based on the external examination of the stomach and intestines, and they note that the test is not reliable on its own, which is why it is only supportive.

• It tests the gut, not the lung — it is a test of 'second life' (life after birth, when swallowing air begins) rather than of breathing as such.
• Putrefaction produces gas in the gut as well, so decomposition can again give a false positive.
• Milk or food inside the stomach or intestine is far more convincing evidence of live birth, but it is only occasionally found.
• It is used alongside the hydrostatic test, lung histology and cord microscopy, never in place of them.

Viability — the ability to survive outside the uterus — is judged from the gestational age estimated from the body length, weight and the ossification centres present in the bones. In one forensic case report, the presence of ossification centres in the sternum, calcaneum and talus led to an estimate of 34 to 36 weeks, which was interpreted as clearly viable. Viability and live birth are separate questions: a baby can be viable and still be stillborn.

A full examination includes the external examination, complete autopsy, histology, toxicology where indicated, and review of the maternal obstetric records. The aim is to separate deaths from natural causes (including those that happen before or around birth) from deaths due to violence or neglect. Published case reports also stress the social background — stigma, extramarital pregnancy, lack of contraception and untreated maternal mental illness — which is relevant to the medicolegal history but not to the autopsy diagnosis.

• Definition-type — live birth needs complete expulsion plus a sign of life; stillbirth has none.
• Test-matching — hydrostatic test = lungs; Breslau's second life test = stomach and intestines.
• Fallacies — putrefaction, artificial respiration and birth-canal air give false-positive floating; prematurity and lung disease can give false-negative sinking.
• Law — BNS section 91 (acts before birth to prevent live birth), 93 (abandonment of a child under 12), 94 (concealment of birth), 103 (murder); explanation to section 100 (a child need not have breathed).
• Evidence ranking — milk or food in the stomach is conclusive of live birth; cord histology and tissue vital reaction support it.