The purpose of this study is to describe the population pharmacokinetic characteristics of piperacillin/tazobactam after intravenous administration in pregnant women during pregnancy and delivery, and to evaluate pharmacodynamic effectiveness and safety of piperacillin/tazobactam in pregnant women whose baby are at high risk of developing early-onset sepsis after birth.

Inclusion Criteria:

• Patients over 18 years old;
• Pregnant women whose baby are at high risk of developing early-onset sepsis after birth have indications to use preventive or therapeutic antibiotics, and the antibiotics used are PIP/TAZO；
• Patients and their families are fully aware of the research content and sign the informed consent form.

Exclusion Criteria:

• Intolerance or serious adverse reactions to antibiotic use;
• Patients who stopped using PIP/TAZO more than 24 hours before delivery;
• Receiving other systemic trial drugs;
• There are other factors that the researchers think are not suitable for inclusion

The research population of this study is pregnant individuals whose baby at high risk of developing early-onset sepsis after birth.