**3. Results**

## **3.1 The effect of age on retrieval of oocyte numbers**

Patient age was plotted as a function of oocyte number for 136 IVF egg retrieval patients, as shown in **Figure 1**.

**Figure 1** shows that the number of collected oocytes declines as a function of patient age. Greater number of oocytes were collected from younger patients than for older patients. The negative correlation demonstrates that as age increases, the number of retrieved oocytes is reduced. The correlation coefficient was calculated to be r = −0.66, which is also indicative of a negative correlation between patient age and oocyte numbers.

### **Figure 1.** *The correlation of patient's age and collected oocyte numbers.*

*Impact of Body Mass Index (BMI) on Retrieval of Oocyte Numbers in* In Vitro *Fertilization… DOI: http://dx.doi.org/10.5772/intechopen.111781*

### **3.2 Relationship between age and BMI**

There was no relationship between patient age and body mass index (**Figure 2**). The correlation coefficient is low (r = 0.11) and shows no statistical significance (p > 0.05). The averages of patient height, weight, BMI, and oocyte numbers in relationship to age ranges are represented in **Table 1**.

**Table 1** shows that there was no significant difference in the patient's height, weight, BMI, and oocyte maturity in various age ranges (p > 0.05). However, as age increases, the collected number of oocytes significantly decreased (p < 0.05).

### **3.3 Scatter diagram of patient body mass index and retrieval oocyte numbers**

The number of eggs retrieved was plotted as a function of BMI (**Figure 3**). Most patients were in the normal body weight category (18.4–24.9 kg/m2 ). There were more overweight patients (24.9–29.9 kg/m2 ) and obese patients (>30 kg/m2 ) than underweight (<18.4 kg/m<sup>2</sup> ) patients. The correlation coefficient between BMI and retrieved oocyte number was calculated to be r = −0.4177. The negative relationship indicates that as BMI increases, the number of oocytes collected decreased. The statistical test of correlation coefficient shows significant difference (P < 0.05).

### **3.4 The effect of patient's BMI on retrieval of oocyte numbers**

According to BMI classification, 136 patients undergoing IVF oocyte retrieval were divided into four groups: BMI < 18.4, BMI 18.5–24.9, BMI 25–29.9, and BMI > 30, representing underweight, normal weight, overweight and obese, respectively. Patient's retrieval oocyte number and oocyte maturation rate have been analyzed (**Table 2**).


### **Table 1.**

*Basic information from collected data in relation to BMI and oocyte numbers at different age ranges.*

**Figure 3.** *A scatter diagram of the relationship between body mass index and oocyte retrieval number.*

Based on **Table 2**, there is no significant difference in patient's height, in different BMI groups, but as patient weight increases, the BMI shows an obvious big. The overweight patients (BMI 25–29.9) had significantly fewer retrieved oocytes than normal-weight patients. Similarly, obese patients (BMI >30) had significantly fewer retrieved oocytes than normal-weight and overweight patients (p < 0.01). Observing oocyte maturity, the number of matured oocytes in obese patients was significantly lower than that of normal-weight and overweight patients (p < 0.05). Thus, obese women had lower oocyte maturation rate. **Figure 4** displays the number of retrieved oocytes and maturation rates in different BMI categories. This figure shows that as BMI increases, the numbers of retrieved oocytes and maturation rates are significantly reduced.

*Impact of Body Mass Index (BMI) on Retrieval of Oocyte Numbers in* In Vitro *Fertilization… DOI: http://dx.doi.org/10.5772/intechopen.111781*


*Note: letters a, b and c indicate significant difference (p < 0.05). The star \* shows only one patient with BMI <18.4 in collecting 136 patients. Although it does not have any statistical significance, it shows that this patient had enough of the number of retrieved oocytes and good maturity.*

### **Table 2.**

*The relationship between patient BMI and number of retrieved oocytes.*

### **Figure 4.**

*Numbers of collection oocytes and maturation oocytes in various BMI patient groups. Note: Underweight group just had one patient with BMI <18.4.*

### **4. Discussion**

Infertility has affected more than 180 million people worldwide and has become an ongoing critical reproductive issue over recent decades [3]. Currently, the assisted reproductive technologies (ARTs) have been an effective measure to treat infertile couples in conceiving a child. However, the success of ART is closely associated with several demographic characteristics and physical conditions, including maternal age, female body mass index, potential diseases, lifestyle, and various environmental factors [4]. BMI has a significant effect on *in vitro* fertilization outcome in especially women. Women with overweight status and obesity status have been associated with higher infertility rates. In this study, we examined whether BMI affects retrieval

of oocyte numbers and oocyte maturity. Our results showed that BMI significantly affected collection of oocyte numbers and its maturation rate. The overweight patients had significantly fewer oocyte numbers than that of normal weight patients. Similarly, obese patients had fewer oocyte numbers than normal-weight and overweight patients. Obese patients' oocyte maturation rate was also much lower than normal and overweight patients. It has been suggested that obesity could have a detrimental effect on oocytes and endometrium [5] because obese women have a poor response to ovarian stimulation, and thereby need higher doses of gonadotropin hormone injections [6]. Thus, normal doses of medication injection for obese women may result in not enough matured oocytes retrieved.

However, according to the World Health Organization, being underweight is much less common with a prevalence of less than 5%, whereas having excess body weight constitutes around 50% of the adult population in developed societies [7]. As a result, fewer research and publication is generated on the negative impact of being underweight on spontaneous and assisted conception. The greatest concerns for underweight women in trying to conceive include the obstetric complications related to nutrition levels for the mother and fetus. This leads to increased risks of anemia, impaired weight gain, preterm delivery, low birth weight, postnatal complications, etc. In our collecting 136 patients, it is disappointing that there was only one patient in BMI < 18.4 group. Thus, we could do a statistical analysis for underweight group. We just listed this underweight Woman with a total of collected 20 oocytes and 16 matured oocytes. It is very difficult to be able to make conclusions regarding underweight patients and IVF treatment in this study.

The number of oocytes collected from women of different BMIs also depends on the age of the patient. We first analyzed the relationship between patient age and retrieved oocyte quantities. Similar to previous research [8], the number of oocytes retrieved and female age have a close association. This relationship represents a negative correlation coefficient (r = −0.66) between patient age and oocyte numbers, thereby indicating that the number of oocytes collected will significantly reduce as a patient is older. For example, although one patient with BMI < 18.4 in our study was underweight, her age was just 24 years old, and she might donate 20 oocytes and had 16 matured oocytes for IVF.

Also, our study indicated that there was no close relationship between age and BMI. The irregular dispersion of the scatter diagraph displays a low correlation coefficient (r = 0.11). Conversely, many reports have indicated a positive correlation between age and weight, where an increase in adult age is commonly associated with increased body weight and thus BMI. However, our results did not find any association between the two variables. This may be due to a limited age range of patients in the study. In other words, our study population may have limited generalizability because the infertile patients who have undergone IVF treatment ranged between 20 to 45 years old. Patients' ages outside of this range were excluded from the analysis. Because of the limited age range, it is possible that weight gain is seen among women outside of this spectrum.

The original design of this study was aimed to analyze the effect BMI has on female IVF outcomes, which also included analyzing the quantity of embryo production and live birth. However, due to limitations of data quantity regarding these two variables, we were unable to analyze the numbers of embryo fertilization and live birth rates. Furthermore, embryo formation and patient pregnancy may be affected by numerous factors, including male sperm quality, female endometrium quality, prenatal complications, etc. Therefore, we concentrated on the association between

*Impact of Body Mass Index (BMI) on Retrieval of Oocyte Numbers in* In Vitro *Fertilization… DOI: http://dx.doi.org/10.5772/intechopen.111781*

female BMI and oocyte production and retrieval numbers. Results from this study may be a reflection of current infertile patient population who are seeking IVF treatment.

### **5. Conclusion**

In summary, our study further verified that the quantity of oocyte retrieval and female age have a close association, where the age of a female significantly affects the number of oocytes that can be fertilized for artificial or natural conception. Thus, we further conclude that as age increases, the number of oocytes retrieved during an IVF treatment is significantly reduced. We did not find a close relationship between infertile female age and BMI; however, our results indicated that BMI has a strong influence on oocyte quantities and maturation rates. Overweight patients tended to have significantly fewer oocytes than that of normal weight patients. Likewise, obese patients have even fewer oocytes than that of normal-weight and overweight patients. Conversely, the underweight patient did not seem to have a difference in oocyte number and maturation rate, but we cannot conclude significant findings from this group since a greater sample size is required. Analysis of the study may be used by IVF physicians and practitioners to facilitate an optimal IVF treatment program for infertile patients seeking to conceive.

### **Acknowledgements**

The author is sincerely grateful to Dr. Randi Weinstein for her ardent supervision, data collection, and editorial assistance during preparations of the thesis.

### **Author details**

Linda Wu1 and Bin Wu2 \*

1 Physiology and Medical Sciences, University of Arizona, Tucson, Arizona, USA

2 Arizona Center for Reproductive Endocrinology and Infertility, Tucson, Arizona, USA

\*Address all correspondence to: bwu13@yahoo.com

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