Perinatal and maternal mortality

Introduction

Perinatal mortality is an important indicator of maternal care, health and nutrition; it also reflects the quality of obstetric, neonatal and paediatric care. The understanding of perinatal mortality statistics is vital in enabling the development of a high-quality approach to the surveillance of the causes of deaths, allowing health care systems to develop prevention strategies and to help clinicians and parents to understand the cause of death of their newborn in order to plan effective monitoring strategies for future pregnancies.

Definitions

The World Health Organization (WHO), in recognizing the importance of international comparison of perinatal and neonatal mortality, coordinates the compilation of health statistics and encourages member countries to rely on the same definitions when comparing the statistics. However, there remain differences in the definitions of perinatal mortality between some countries, reflecting the definition of viability and resources in the individual countries.

The definitions are drawn from the tenth revision of the International Classification of Diseases (ICD-10). The key definitions are:

• Live birth: Complete expulsion or extraction from its mother of a product of conception, irrespective of the duration of the pregnancy, which, after such separation, breathes or shows any other evidence of life, such as beating of the heart, pulsation of the umbilical cord or definite movement of voluntary muscles, whether or not the umbilical cord has been cut or the placenta is attached; each product of such a birth is considered live-born.

• Stillbirth or fetal death: Death prior to the complete expulsion or extraction from its mother of a product of conception, irrespective of the duration of pregnancy; the death is indicated by the fact that after such separation the fetus does not breathe or show any other evidence of life, such as beating of the heart, pulsation of the umbilical cord or definite movement of voluntary muscles.

The definition recommended by the WHO for international comparison is a baby born with no signs of life at or after 28 weeks’ gestation (or birth weight of 1000 g). Further definition provided by ICD-10 gave priority of birth weight over gestation as follows:

• Late fetal death – 1000 g or more, 28 weeks or more or 35 cm or more

• Early fetal death – 500 g or more or 22 weeks or more or 25 cm or more

• Miscarriage as a pregnancy loss before 22 completed weeks of gestational age

• Perinatal period: Commences at 22 completed weeks (154 days) of gestation and ends 7 completed days after birth.

• Neonatal period: Begins with birth and ends 28 complete days after birth. Neonatal deaths may be subdivided into early neonatal deaths , occurring during the first 7 days of life (0–6 days), and late neonatal deaths , occurring after the seventh day but before the twenty-eighth day of life (7–27 days).

In the UK, the definitions are different, reflecting the survival rates and concept of viability. The present legal definitions that apply to England and Wales are as follows:

• Stillbirth: A baby delivered at or after 24+0 weeks gestational age showing no signs of life, irrespective of when the death occurred.

  • Antepartum stillbirth: A baby delivered at or after 24+0 weeks gestational age showing no signs of life and known to have died before the onset of care in labour.

  • Intrapartum stillbirth: A baby delivered at or after 24+0 weeks gestational age showing no signs of life and known to have been alive at the onset of care in labour.

• Neonatal death: A liveborn baby (born at 20+0 weeks gestational age or later, or with a birth weight of 400 g or more where an accurate estimate of gestation is not available) who died before 28 completed days after birth.

  • Early neonatal death: A liveborn baby (born at 20+0 weeks gestational age or later, or with a birth weight of 400 g or more where an accurate estimate of gestation is not available) who died before 7 completed days after birth.

  • Late neonatal death: A liveborn baby (born at 20+0 weeks gestational age or later, or with a birth weight of 40 g or more where an accurate estimate of gestation is not available) who died after 7 completed days but before 28 completed days after birth.

• Perinatal death: Death of a fetus or a newborn in the perinatal period that commences at 24 completed weeks’ gestation and ends before 7 completed days after birth.

In Australia and New Zealand, stillbirth is defined as ‘Death prior to the complete expulsion or extraction from its mother of a product of conception of 20 or more completed weeks of gestation or of 400g or more birth weight where gestation is not known. The death is indicated by the fact that after such separation the fetus does not breathe or show any other evidence of life, such as beating of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles’.

Mortality rates

The current definitions are as follows:

• Stillbirth rate (SBR): The number of stillbirths per 1000 total births

• Neonatal mortality rate (NMR): The number of neonatal deaths occurring within the first 28 days of life per 1000 live births

• Perinatal mortality rate (PNMR): The number of stillbirths and early neonatal deaths (those occurring in the first week of life) per 1000 total births (live births and stillbirths)

The global picture

In 2000, the United Nations (UN) member states pledged to work towards a series of Millennium Development Goals (MDGs), including the target of a three-quarters reduction in the 1990 maternal mortality ratio (MMR; maternal deaths per 100,000 live births), to be achieved by 2015. This target (MDG 5A) and that of achieving universal access to reproductive health (MDG 5B) together formed the two targets for MDG 5: Improve maternal health. Disappointingly, at the end of the MDG era, stillbirth rates declined more slowly since 2000 than either maternal mortality or mortality in children younger than 5 years. Worldwide, the number of stillbirths declined by 19.4% between 2000 and 2015, representing an annual reduction rate (ARR) of 2%. This rate of reduction was lower when compared with that for MMR (ARR = 3.0%) and under-5 mortality rate (ARR = 3.9%) for the same period.

In an attempt to improve the classification of maternal deaths, the WHO applied some modifications to the definitions of ICD-10. This is known as ICD-Maternal Mortality (MM).

This defined death occurring during pregnancy, childbirth and the puerperium as the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the cause of death (obstetric and non-obstetric).

In 2015, there were 2.6 million stillbirths globally, with more than 7178 deaths a day, representing a stillbirth rate (SBR) of 18.4 per 1000 births. Ninety-eight percent occurred in low- and middle-income countries. The highest stillbirth rates are in conflict and emergency areas. About 60% of stillbirths are in rural areas. The SBR in sub-Saharan Africa is approximately 10 times that of developed countries (29 versus 3 per 1000 births). Among the 133 million babies born alive each year, 2.8 million die in the first week of life. The patterns of these deaths are similar to the patterns for maternal deaths; this correlates with areas of low-skilled health professional attendants at birth. Ten countries, many of these in Africa and South Asia, account for two-thirds of stillbirths and most neonatal (62%) and maternal (58%) deaths estimated in 2015.

In an effort to continue to improve the perinatal mortality rates worldwide, the Every Newborn Action Plan (ENAP) was launched in mid-2014 with a World Health Assembly resolution, endorsed by all countries. ENAP targets the reduction of the NMR to 12 or fewer per 1000 live births and stillbirths to 12 or fewer per 1000 births in all countries by 2030. Both the neonatal and stillbirth reduction targets are included as core indictors in the Every Woman, Every Child Global Strategy for Women’s, Children’s and Adolescents’ Health (2015–2030) ( Fig. 5.1 ).

Developed countries have seen a steady fall in the PNMR over the last 30 years. In the United Kingdom, MBRRACE-UK (Mothers and Babies: Reducing Risks through Audits and Confidential Enquiries across the UK) published the third annual report of the national perinatal mortality statistics for 2015. This showed a PNMR of 5.61 per 1000 births, comprising an SBR of 3.87 and an NMR of 1.74 per 1000 births. Whilst the SBR has shown a downward trend since 2013, the NMR has only marginally reduced.

The perinatal-related mortality rate in 2015 in New Zealand was reported as 9.7/1000 births. Whilst this rate was the lowest since data were collected by the Perinatal and Maternal Mortality Review Committee in 2007, it did not show a statistically significant trend in improvement.

The Australian Institute of Health and Welfare (AIHW, 2017) reported that in the 20-year period from 1993 to 2012, the overall PNMR remained stable at around 10 deaths per 1000 live births. In 2015, there were 9 perinatal deaths for every 1000 births, a total of 2849 perinatal deaths. This included 2160 fetal deaths (stillbirths), or 7 fetal deaths per 1000 births, and 689 neonatal deaths, a rate of 2 neonatal deaths per 1000 live births.