With an growing number of people on a strict plant-based diet, its potential effect on pregnancy and lactation becomes increasingly important. It is, however, unclear how obstetric caregivers currently handle and think about a strict plant-based diet in pregnancy. The aim of the study was therefore to evaluate the self-reported knowledge and advice given by Dutch obstetric caregivers and dietitians when treating pregnant women on a strict plant-based diet. A cross-sectional study was performed by sending an online survey to Dutch midwife practices, obstetricians, and dietitian practices. Descriptive statistics are reported. A total of 121 midwives, 179 obstetricians, and 111 dietitians participated in this study. The majority of midwives (80.2%) and obstetricians (93.9%) considered a strict plant-based diet to be a significant risk factor for nutrient deficiency during pregnancy. Maternal dietary preferences, including a potential strict plant-based diet, were discussed at the first prenatal appointment by 59.5% of midwives and 24.1% of obstetricians. A self-reported lack of knowledge concerning the strict plant-based diet was mentioned by 66.1% of midwives and 75.4% of obstetricians. Obstetric caregivers mostly considered the identification of this dietary habit and subsequent referral to a dietitian or a reliable website as optimal care for pregnant women on the strict plant-based diet. However, only 38.7% of dietitians indicated to have sufficient knowledge to counsel these women. Although obstetric caregivers thought that a strict plant-based diet in pregnancy may lead to increased risks of nutritional deficiencies, the majority report to have insufficient knowledge to provide adequate advice. Only a minority referred these women to dietitians, of whom a minority indicated to have adequate knowledge on this specific diet. These results suggest that current care is suboptimal for an increasing number of pregnant women. Women on a strict plant-based diet could benefit from increased knowledge about this topic among obstetric caregivers and dietitians, as well as from clear guidelines regarding this diet during pregnancy.