Fertility, ART, and Pregnancy Outcomes: Key Concepts and Statistics

What is the number of births?

A count of births occurring in a population during a defined period.

What is total fertility rate (TFR)?

A summary based on current age-specific fertility rates. It estimates the average number of births a woman would have if those rates continued throughout reproductive life.

What is replacement fertility?

The fertility level at which one generation is replaced by the next, excluding migration effects.

What is an age-specific fertility rate?

Births per 1000 women in a defined age group.

Why can TFR and the total number of births move differently?

TFR summarises fertility rates, while birth counts also depend on the number and age structure of people in reproductive age groups.

What must be identified before interpreting any fertility graph?

The exact measure and denominator. Birth count, TFR, births per 1000 women and percentage of mothers are not interchangeable.

What major fertility pattern is associated with the Great Depression in the lecture graph?

A marked low point in births and fertility.

What major trend followed the Great Depression?

Fertility and births increased and reached a peak during the baby boom.

When was the contraceptive pill introduced and when did it become available on the PBS?

Introduced in 1961 and available on the Pharmaceutical Benefits Scheme in 1972.

In what year did Australian TFR fall below replacement fertility?

1976.

Why do labelled historical events on a fertility graph not prove causation?

A time association only provides context. Multiple social, economic, technological and demographic factors can contribute to the observed change.

Which factors may interact to change reproductive behaviour at the population level?

Contraception, education, employment, partnership patterns, economic conditions, health care and social expectations.

How has the age pattern of fertility shifted in Australia?

Fertility has shifted away from younger age groups and toward older age groups.

Which age groups historically had especially high fertility rates?

Women aged 20 to 24 and 25 to 29 years.

Which older age groups have become more prominent contributors to fertility?

Women aged 30 to 34, 35 to 39 and 40 to 44 years.

What proportion of mothers were aged 30 to 39 years in 1975?

Fewer than 20%.

What proportion of mothers were aged 30 to 39 years in 2022?

50%.

Why does later reproduction matter biologically and clinically?

Reproductive ageing affects conception probability, ART success and pregnancy risk, and it changes the type and amount of health-system support required.

Which age-related ART research issue includes both parents?

The implications of maternal and paternal age for ART success and offspring health.

How can population statistics guide reproductive research and health planning?

They identify who is affected, how common an outcome is, whether it is changing and where clinical or research resources may be needed.

Give a research question that moves beyond describing delayed childbearing.

Example: Which social, economic and health-system factors contributed most to delayed childbearing in Australia?

What does a TFR below replacement mean?

Fertility alone would not maintain population size over the long term. Migration and existing age structure can still affect actual population size.

Why is the number of births influenced by population structure?

A population with more people in high-fertility age groups can have more births even when individual fertility rates are unchanged.

Why are age-specific fertility rates useful?

They show which ages contribute most to fertility and reveal shifts in the timing of reproduction that an overall TFR can conceal.

What does ART stand for?

Assisted reproductive technology.

Which ART examples are named in the unit materials?

In vitro fertilisation (IVF) and frozen embryo transfer (FET).

How has the number of ART treatment cycles changed since 2002?

It has more than doubled in Australia.

How many ART cycles were recorded in Australia in 2023?

103,556 cycles.

What was the Australian ART cycle rate in 2023?

18.7 cycles per 1000 women.

How has the proportion of people giving birth through ART changed since 2002?

It has more than doubled.

What is the relationship between ART use and fertility at older ages?

The study highlighted in the lecture indicates that increased fertility at older ages is largely driven by increasing ART use.

Why is one ART cycle not equivalent to one person or one live birth?

A person may undergo multiple cycles, and some cycles do not result in pregnancy or live birth. Always use the outcome named by the statistic.

What ART research question concerns parental age?

How maternal and paternal age affect treatment success and offspring health.

Which child-health outcomes are raised as concerns in ART research?

Low birth weight, preterm birth and developmental anomalies, including why increased risks are reported in some ART-conceived groups.

What is the epigenetic ART research question?

Whether gamete handling, embryo culture or early developmental conditions alter gene regulation without changing the DNA sequence.

How might AI and machine learning be used in ART research?

To investigate methods that improve embryo selection, implantation or live-birth outcomes.

What long-term maternal ART question is identified?

How ART affects the health and wellbeing of mothers over time.

What regulatory challenge is created by ART?

Law and policy must adapt to changing technologies, demographics and ethical issues.

How fragmented is the ART legislative environment described in the lecture?

More than 40 pieces of legislation across nine Australian jurisdictions.

What should the population component of an ART research question specify?

Exactly whose outcome is being studied, such as a maternal age group, treatment population or group of children conceived through ART.

What can serve as the exposure, intervention or comparator in an ART question?

Age, treatment type, embryo culture condition or selection method can be the exposure. Comparators may include younger groups, non-ART conception, alternative treatments or standard practice.

Which outcomes and timeframes can be specified in an ART question?

Outcomes may include fertilisation, implantation, clinical pregnancy, live birth, maternal health or child health. Timeframes may be immediate, pregnancy, childhood, adulthood or intergenerational.

Why is pregnancy health described as a determinant of population health?

Pregnancy is common and can affect the pregnant person and child immediately, across both life courses and potentially across generations.

Approximately what proportion of women globally experience pregnancy at some point in life, according to the lecture source?

Approximately 85%.

What two timescales of pregnancy-health effects must be considered?

Immediate effects during pregnancy and around birth, plus long-term effects on the pregnant person and child.

What global estimate is shown for preterm birth?

10.6 per 100 live births, with a 95% confidence interval of 8.7 to 11.9.

What global estimate is shown for preeclampsia?

2.16 per 100 pregnancies, with a 95% confidence interval of 2.11 to 2.22.

What global estimate is shown for gestational diabetes?

14.0 per 100 pregnancies of at least 24 weeks, with a 95% confidence interval of 13.97 to 14.04.

What global estimate is shown for low birth weight?

14.6 per 100 live births, with a 95% confidence interval of 12.4 to 17.1.

What estimates are shown for maternal life-threatening complications and postpartum haemorrhage?

Maternal life-threatening complication, 1.4 per 100 deliveries. Postpartum haemorrhage, 6.09 per 100 births.

What estimates are shown for chorioamnionitis, sepsis and hypoxic ischaemic encephalopathy?

Chorioamnionitis, 3.9 per 100 births. Sepsis, 0.05 per 100 births. Hypoxic ischaemic encephalopathy, 0.15 per 100 live births.

Why do denominators matter when comparing pregnancy-complication rates?

Rates may use live births, all births, pregnancies or deliveries. Values with different denominators are not directly comparable without accounting for the population counted.

What does a confidence interval communicate?

A range expressing uncertainty around an estimated population value.

How many mothers and babies were recorded in Australia in 2023?

281,099 mothers gave birth to 285,305 babies.

What is low birth weight (LBW)?

Birth weight below 2500 g.

What were the Australian LBW proportions in 2023?

7.2% of all births, 6.6% of liveborn babies and 77% of stillborn babies.

Which groups had the highest LBW rates?

The youngest and oldest maternal age groups, smokers, people living in remote areas and people in socioeconomically disadvantaged areas.

How has the overall Australian LBW rate changed over time?

It has remained stable over time.

What proportion of liveborn LBW babies were preterm?

57%.

Why are LBW and preterm birth related but not equivalent?

LBW describes weight, while preterm describes timing. A term baby can have restricted growth and LBW, while a preterm baby can weigh 2500 g or more.

What is preterm birth?

Birth before 37 completed weeks of gestation.

What proportion of Australian births were preterm in 2023?

8.4%.

How has the Australian preterm-birth rate changed over time?

It has remained stable for more than 40 years.

What smoking-related preterm-birth rates are shown?

Approximately 14% among smokers versus 7.8% in the comparison group shown.

How do multiple pregnancies affect preterm-birth risk?

Twins and other multiples have higher preterm-birth rates.

Why is preterm birth a major clinical problem?

It is identified as the main cause of neonatal mortality and is associated with increased short-term and long-term morbidity.

Why does a stable preterm-birth rate not mean the problem is solved?

A common adverse outcome can remain a major burden even without increasing. Its persistence indicates that prediction, prevention and treatment remain difficult.

What is preeclampsia?

A pregnancy-specific multisystem disorder characterised by hypertension plus one or more additional maternal organ or fetal-placental features.

Which additional features of preeclampsia are listed?

Protein in urine, neurological symptoms, oedema and fetal growth restriction.

Which groups have the highest rates of gestational hypertension in the data presented?

Mothers older than 40 years and first-time mothers.

How does gestational hypertension differ from preeclampsia?

Gestational hypertension is high blood pressure arising in pregnancy without the full additional features. Preeclampsia includes hypertension plus evidence of broader organ or fetal-placental involvement.

How did the proportion of Australian mothers with gestational diabetes change from 2014 to 2023?

It increased from 8.3% to 17%.

What are the maternal risks of uncontrolled gestational diabetes?

Increased risk of later type 2 diabetes and labour complications.

What are the fetal or child risks of uncontrolled gestational diabetes?

Macrosomia, neonatal hypoglycaemia and long-term metabolic dysregulation.

Why must the rise in gestational-diabetes diagnosis be interpreted carefully?

It may reflect changing risk factors, age or body composition, screening practices, diagnostic criteria, clinical practice or a combination.

Which broad factors are associated with pregnancy complications in the lecture?

Older age at reproduction, increasing obesity and co-existing medical problems.

What three-way interaction contributes to pregnancy complications?

The interaction among the pregnant person, the developing baby and the placenta.

Why is pregnancy research biologically difficult?

The pregnant person, fetus and placenta interact, biology changes across gestation, social determinants affect biological pathways, and the in-utero environment is difficult to access directly.

Why are controlled experiments in human pregnancy limited?

Ethical constraints restrict experimental manipulation, and reproductive effects may take gestation, childhood, adulthood or generations to appear.

Why are experimental models needed for 'why' and 'how' questions?

Mechanistic questions often require controlled intervention. Models allow defined factors to be manipulated in hypothesis-driven experiments.

What is hypothesis-driven research?

Start with a specific proposed explanation, manipulate or compare a defined factor, measure a predicted outcome, and use the result to support, refine or reject the explanation.

Which main experimental model types are introduced?

Primary cells and tissues, human or animal cell lines, organoids, animal models, and transgenic mouse or rat models.

What does in vitro mean?

Cells or simplified biological components studied in a controlled laboratory environment outside a whole organism.

What does ex vivo mean?

Fresh or preserved tissue studied outside the organism while retaining some native structure and multiple cell types.

What does in vivo mean?

Study within a living organism, including integrated physiology and systemic interactions.

Does greater biological complexity automatically make a model better?

No. The best model is the simplest model that can validly answer the question while preserving the essential biology.

What are primary human cells?

Cells obtained directly from human tissue, such as a biopsy, then separated and cultured outside the body.

How are primary cells used experimentally?

Researchers control culture conditions, add or remove factors and observe changes in cell signalling, invasion, secretion or other functions.

What primary-cell example is used in the lecture?

First-trimester human extravillous trophoblast cells were used to study invasion and the effect of leukaemia inhibitory factor (LIF).

What is extravillous trophoblast (EVT)?

An invasive placental trophoblast cell type involved in maternal tissue invasion during early placental development.

What conclusion was drawn from the LIF and EVT example?

LIF can regulate EVT invasion and may have an important role in early placental development.

What are the major strengths of primary human cells?

Human species relevance, retention of source-tissue features, controlled manipulation and usefulness for cell-level mechanisms.

What growth limitation applies to primary cells?

They undergo a finite number of divisions.

How do access and donor variability limit primary-cell research?

Tissue requires donation and ethics approval, and biological differences among donors can increase experimental variability.

What biological context is lost when primary cells are isolated?

Interactions with other cells, tissue architecture, blood flow, endocrine signals, immune influences and whole-body physiology.

Why might an in-vitro primary-cell response not be reproduced in vivo?

The living organism contains interacting tissues, systemic signals and physical conditions absent from the isolated culture.

What is a primary human tissue or ex-vivo model?

A model in which tissue is studied outside the body while retaining more of its original structure and cell diversity than isolated cells.

What ex-vivo disease model is shown in the lecture?

Cryopreserved endometriotic tissue fragments used to model endometriosis and its fibrotic microenvironment.

What did cryopreservation allow in the endometriosis model?

Viable tissue could be stored, thawed, used to test therapies and exchanged between laboratories.

What are the main strengths of ex-vivo tissue?

It preserves multiple cell types, local architecture and disease-specific features, and permits direct testing of treatments on human tissue.