Assisted Reproductive Technology Practices and Outcomes

Assisted reproductive technology (ART) encompasses a suite of medical interventions designed to aid conception when natural fertility is compromised. Central to ART are in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI), in which eggs and sperm are manipulated outside the body to achieve fertilisation. Embryos may be transferred in the same cycle (fresh transfer) or after cryopreservation (frozen embryo transfer), with advances in laboratory culture and freezing protocols markedly improving survival and implantation rates. Embryo selection techniques—ranging from morphological grading to preimplantation genetic testing—seek to maximise the chance of a healthy singleton pregnancy and reduce multiple births, which remain associated with higher risk of prematurity and neonatal complications. Single embryo transfer policies have been widely adopted to curb twin and higher-order gestations, while double embryo transfers persist in certain age groups or clinical contexts to enhance live birth rates. Cryopreservation extends opportunities for fertility preservation, donor programme scheduling and cycle flexibility. Outcome measures such as clinical pregnancy rate, live birth rate and neonatal wellbeing guide both individual treatment decisions and national policies. International registry data reveal growing cycle volumes, a steady shift towards frozen transfers and an increasing emphasis on single embryo transfer. Ongoing research addresses optimisation of stimulation protocols, embryo assessment and long-term health of ART-conceived offspring, underlining the global significance of ART for reproductive autonomy and public health.

Research from Nature Portfolio

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Assisted Reproductive Technology Practices and Outcomes publication trend

The graph below shows the total number of articles in assisted reproductive technology practices and outcomes across all publications each year (not limited to Nature Index journals).

Technical terms

In vitro fertilisation (IVF): Laboratory fertilisation of eggs with sperm outside the body.

Intracytoplasmic sperm injection (ICSI): Direct injection of a single sperm into an egg to achieve fertilisation.

Frozen embryo transfer (FET): Transfer of embryos that have been cryopreserved and later thawed for uterine implantation.

Single embryo transfer (SET): Placement of one embryo per cycle to reduce multiple births.

Double embryo transfer (DET): Placement of two embryos per cycle to increase the chance of pregnancy but with higher multiple-birth risk.

Preimplantation genetic testing (PGT): Genetic analysis of embryos prior to transfer to detect chromosomal abnormalities.

Cryopreservation: Freezing of gametes or embryos for future use.

Live birth rate (LBR): Proportion of cycles resulting in at least one live infant.

Multiple birth rate (MBR): Proportion of pregnancies resulting in twins or higher-order multiples.

References

1. ART in Europe, 2019: results generated from European registries by ESHRE†. Human Reproduction (2023).
2. Effect of frozen-thawed embryo transfer with a poor-quality embryo and a good-quality embryo on pregnancy and neonatal outcomes. Reproductive Biology and Endocrinology (2024).
3. Comparison of frozen-thaw blastocyst transfer strategies in women aged 35–40 years: a retrospective study. Frontiers in Endocrinology (2023).