Most laboratories use HEPES buffer solution for oocyte retrieval because it provides pH stability through buffering action. In contrast, there are laboratories that use workstations which provide CO₂ and temperature stability during oocyte collection. When this type of workstation is used, HEPES buffer solution is not required. In laboratories working without a dedicated workstation, the recovery and processing of oocytes should be done quickly to maintain optimal oocyte temperature and pH conditions.

Women over the age of 40 years are at a higher risk of early pregnancy complications such a miscarriage or ectopic pregnancy. They are also more likely to have pre-existing medical conditions which further increase their risk of early pregnancy pathology, for example, previous pelvic inflammatory disease leading to a tubal ectopic, or uncontrolled diabetes increasing the risk of a miscarriage. Women in this age group are also more likely to have conceived through fertility treatment, and may present with complications of this, such as multiple pregnancy or ovarian hyperstimulation syndrome. A woman’s history of assisted reproductive technology and pre-existing subfertility is significant not only in accurately dating the pregnancy but also with regards to the psychological impact in case of a poor outcome. Early pregnancy units have become well established in most hospitals as a dedicated department providing specialist early pregnancy care. This chapter provides an overview of the optminal management of the first trimester of pregnancy for women over 40 and the management of the common conditions.

The number of eggs retrieved is an important prognostic factor for IVF outcome, with low egg number associated with a lower likelihood of success. ‘Natural’ and ‘mild’ approaches to ovarian stimulation for IVF intentionally aim to limit the number of eggs retrieved. Hence, they are less effective than standard regimes at achieving live birth, particularly on a cumulative basis. In poor responders, these approaches yield fewer eggs and a higher cancellation rate. The risk of OHSS with standard regimes can be managed using GnRH antagonist, agonist trigger and freeze-all, without compromising the likelihood of live birth. Embryo aneuploidy is not increased by exogenous gonadotropin use. Hence, there is evidence that ‘natural’ and ‘mild’ stimulation reduces the likelihood of having a baby, and no evidence that the risks of standard stimulation are high enough to justify use of ‘natural’ and ‘mild’ IVF in modern practice.