Research conducted July 2019 in Colorado, looked into young mothers (13-22 years old) with singleton pregnancies.3 In this particular study, cannabis exposure was associated with adverse outcomes related to pregnancy and the newborn. Hypertensive disorders of pregnancy in the mother and sponateous preterm birth, stillbirth, and small for gestational age (SGA) newborns were outcomes seen in the study. With gestational hypertension there is the associated risk of intrauterine growth restriction (IUGR) leading to risks for small gestational age (SGA) and/or low birth weight (LBW) newborns. 3
A retrospective medical record review of singleton births was conducted between August 2013 through December 2014 which explored cannabis use in pregnancy based on urine drug screen and the association with infant birthweight.7 Urine drug screens were collected at the beginning of prenatal care and at delivery. Infants born to mothers with cannabis utilization during pregnancy through positive urine testing at presentation for prenatal care and delivery were found to have a significantly lower median birthweight compared to those with negative urine testing.
From past research, there is a similar trend in lower birthweight seen in newborns exposed to cannabis during pregnancy as opposed to newborns that were not.3 The risks for complications perceptible not only in the newborn but also in the mother; made evident in previous research conducted. A study conducted at the University of Colorado discovered lower birthweight and small for gestatational age (SGA) newborns as a result of cannabis use in pregnancy. Their sample included 1206 young women, with 211 identified as using cannabis during pregnancy. Our study utilized a medical database to identify 50 women of reproductive age who used cannabis during pregnancy compared to 50 women who were identified as not using cannabis during pregnancy. These women were chosen for our study through meticulous data identication and collection to ensure the subjects met specific inclusion criteria. The difference in sample size does factor into the results of the studies and their ability to be applicable to the general population. However, in our study the immediate complications at delivery and during the perinatal period for the newborn were negligible.
Previous data suggest cannabis affects glucose and insulin regulation and may affect the fetal growth trajectory.5 In a study completed in October 2017, researchers examined maternal cannabis use and adverse pregnancies outcomes. Results were significant for neonatal morbidity but not specific to any disease or disorder.
A meta-analysis completed July 2019 delved into reviewing and summarizing the existing literature in regards to cannabis use in pregnancy and its effects on the newborn if any. 8 The results showed a level of developmental disruption with increased risk for adverse outcomes to neurodevelopment and increased risk of fetal growth restriction in the newborn. Most of the prenatal research was completed in the 1980s and the usage, frequency and quantities of THC in cannabis used during that particular time period was markedly decreased than present day cannabis. As the potency of cannabis continues to increase, it will be critical to systematically evaluate the long term outcomes of THC-exposed children.6 The paucity of research and evidence has led to many unknowns in that area.
Previous research related to cannabis use in pregnancy has followed women throughout pregnancy longitudinally. In a one year prospective study, a decrease in cannabis use was noted beginning in the first trimester at 32%. Continuing on into the third trimester; a 16% decline in the utilization of cannabis was noted.1 These particular mothers knew they were being followed throughout their pregnancy, so it is possible the Hawthorne Effect had played a part in the results of this study. In our particular research study, which is retrospective in nature, the Hawthorne Effect was virtually eliminated. It is imperative that research be conducted to take into consideration present day cannabis utilization and its frequency of use. Once the effects of cannabis are thoroughly delineated and characterized, patient education and antenatal surveillance can be conducted to assuage the impact on fetal and newborn outcomes. Little is known about the effects of cannabis on the unborn child and therefore this study’s goal was to investigate measures at delivery to determine if differences are seen amongst those who used cannabis during pregnancy from those who did not.
Interestingly enough, we found there was no significant difference between caucasians and non – caucasians, in terms of the level of THC found in the urine during universal screening completed on admission for delivery. Gestational age at birth in those with positive urine testing compared to those with negative urine testing showed no substantial significance which does not appear to have the ability to be applied to clinical practice. The rate of perinatal complications to the newborn was negligible at delivery and in the immediate perinatal period, therefore a sub analysis could not be conducted. Therefore, no difference in the rate of complications in regards to the level of THC in the urine was evident. We found an asociation between maternal cannabis use and birthweight with lower birthweights seen with cannabis use versus non cannabis use. There is significant cannabis use in pregnancy which could also mean clinical significance in regards to preconception counseling of couples during the prenatal period. With increases in medical knowledge regarding cannabis use in pregnancy and its outcomes in pregnancy and the newborn; adequate teaching/counseling can be developed to help ensure proper resources to the family.
Biggest strength of the study was utilizing urine toxicology results alone in data collection and subsequent analysis. This allows for stronger veracity of study results with the hope of utilizing and applying the results to the general population. In addition, we eliminated confounders at the beginning of the study in order to estimate the true impact of cannabis use in perinatal outcomes in the newborn.
Exclusion criteria attempted to be a thorough as possible to eliminate confounders in the results of the study. Hypertensive disorders in pregnancy and prior to pregnancy has an association with intrauterine growth restriction (IUGR). 3 Tobacco use in pregnancy is associated with lower birthweight in infants as well.7
Limitations in regards to this study are due to not quantifying the frequency of cannabis use in pregnancy and the method of use/intake. We only had the levels of THC found in the urine by carboxy acid tetrahydrocannabinol (THC) level in nanograms per milliliter (ng/ml) that was gathered on admission for delivery. The focus of our study was on the outcomes for the newborn at delivery and the immediate perinatal period without looking into growth and development in the newborn and growing infant. In addition, tobacco use was determined by self-report rather than using biological sampling of cotinine. This may have resulted in an underestimation of the effect of tobacco use in pregnancy. Lastly, our sample size may have been small and a larger study may help reveal more delivery complications associated with cannabis use.