I am not an expert on this issue either. I suggest that you ask your physician to speak with the high risk consultant for you or expedite the consult for you.
This is information for you from REPROTOX on-line. I wsh you the best.
Quick take: Based on experimental animal studies and a moderate number of human cases, venlafaxine is not anticipated to increase the risk of congenital anomalies. Transient and usually mild neonatal complications have been reported for venlafaxine and the serotonergic antidepressants.
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Venlafaxine is a bicyclic antidepressant that is a serontonin-norepinephrine reuptake inhibitor. It is available generically in an immediate release preparation and as Effexor, and in an extended release preparation as Effexor XR. According to the manufacturer (Wyeth), venlafaxine did not increase malformations in the offspring of rats given up to 11 times and rabbits given up to 12 times the human dose on a mg/kg basis (2.5 and 4 times the human dose on a surface area basis). Decreased pup weight and viability were noted at 10 times the human dose (on a mg/kg basis) in rats. No comments were made concerning maternal toxicity at these doses. Treatment of pregnant rats with fluoxetine (#1898; 8 mg/kg/d) but not venlafaxine (40 mg/kg/d and 80 mg/kg/d) during the last week of the 3- week gestation resulted in a one-half day decrease in length of gestation (6). Treatment with either drug at doses that did not cause maternal toxicity (fluoxetine 8 mg/kg/d and venlafaxine 40 mg/kg/d) led to a reduction in birth weight. By weaning at postnatal day 25, body weight was the same in all treated and control groups.
The presence in amniotic fluid of venlafaxine and its active metabolite O-desmethylvenlafaxine was demonstrated in a small study (n = 27) (8). During the clinical trials for this drug, ten gestational exposures were identified in which venlafaxine was used for periods ranging from 10 to 60 d (1). Information was available on only four of the exposed infants, all of whom were apparently normal (1).
A collaborative teratology information center study compared the outcome of 150 pregnancies with first trimester venlafaxine exposure to 150 with exposure to other serotonin-reuptake inhibitors and to a control group (n=150) with what were considered by the authors to be trivial exposures (3, 7). There were no significant differences between the three groups in the rates of major malformations, miscarriages or stillbirths. There were two children with major malformations in the exposed group but the nature of the malformations was not specified.
A case series of 11 pregnancies with first trimester exposure to venlafaxine reported 2 induced abortions and 9 healthy babies (5)
Transient neonatal complications have been associated with third trimester exposure to all of the serotonergic antidepressants (See Fluoxetine #1898). There are few reports of complications associated with venlafaxine exposure(9,13,17). There is one case report of mild neonatal complications in a male infant following antenatal exposure to venlafaxine (9). The infant presented with restlessness, hypertonia, jitteriness, irritability and poor feeding. Symptoms improved after a single dose of venlafaxine 1mg and resolved by 8 days postpartum. In a second report, 2 prenatally exposed infants developed seizures postnatally, one at 30 minutes and the other at 24 hours (16). The seizures resolved promptly after treatment with Phenobarbital. The babies were tapered off phenobarbital between 1 and 2 weeks postpartum. Neurodevelopment at one year was reportedly within normal limits. Another study reported on the prevalence of neonatal complications in 60 infants exposed to serotonergic antidepressants at birth. Two children had been exposed to low doses of venlafaxine (37.5-75 mg/d). There were 18 babies with what the authors considered a neonatal abstinence syndrome, 8 of whom had severe symptoms. None of these babies had been exposed to venlafaxine. The drugs of exposure were not specified for the 10 who had a mild syndrome.
Using a comparison with siblings, prenatal exposure to venlafaxine or other antidepressents in 32 infants did not significantly effect physical development or performance on IQ tests (14).
Based on data from 16 lactating women who were taking venlafaxine for depression, this agent and its main active metabolite, O-desmethylvenlafaxine, are excreted in human milk (2,4,10,12,18). In reports by one group, the mean milk/plasma ratio for venlafaxine was 2.5 (range 2.0-3.2) and 2.7 for O-desmethylvenlafaxine (range 2.3-3.2). The mean total infant dose (as venlafaxine equivalents) was 6.4% (5.5-7.3%) of the maternal weight-adjusted dose, with equal amounts of venlafaxine (3.2%) and O- desmethylvenlafaxine (3.2%). The parent compound was found in the plasma of one of the infants exposed to venlafaxine in milk, but measurable levels of O-desmethylvenlafaxine were detected in the plasma of 4 of the 7 infants studied (2,18).
In another study, venlafaxine was detected in 1 of 3 infants, and O-desmethylvenlafaxine was detected in all three. The mean infant serum drug concentration as a percentage of the maternal serum drug concentration (for the parent compound and metabolite) was 10.2% (range 5.3- 19.0)(10). In each of these studies, all of the infants were healthy and showed no acute adverse effects.
Milk levels were reported for 2 breastfed infants exposed to venlafaxine plus quetiapine (#4099) (11). Timing after the dose was not specified. When sampled at 6.5 weeks postpartum, the milk level was 371 nM at a maternal dose of 75 mg/d of venlafaxine. In the second case, at 9.5 weeks, the milk level was 1179 nM at a maternal dose of 225 mg/d. In both cases, infant exposure was estimated as <0.1 mg/kg/d and psychomotor development at 12 months of age was reported to be normal.
Based on 1 case, a group of clinicians have suggested that the active drug in milk may help alleviate withdrawal symptoms in the newborns of mothers taking venlafaxine (15). We note, however, that it is not clear that the neonatal symptoms are due to withdrawal and not to serotonergic activity.